COMPETENCY BASED LEARNING MATERIAL

Sector:
HEATING, VENTILATING, AIR-CONDITIONING AND REFRIGERATION (HVAC/R)
Qualification:
RAC SERVICING (DOMRAC) NCII
Unit of Competency:
SERVICE AND MAINTAIN DOMESTIC REFRIGERATION UNIT

Module Title:

SERVICING AND MAINTAINING DOMESTIC REFRIGERATION UNIT

Technical Education and Skills

Development Authority
ISABELA SCHOOL OF ARTS AND TRADES
CALAMAGUI 2ND, ILAGAN CITY, ISABELA

SUMMARY OFCOMPETENCY-BASED LEARNING MATERIALS

NO UNIT OF COMPETENCIES MODULE TITLE CODE
1 Install domestic refrigeration and Installing domestic HVC723337
air-conditioning (DomRAC) units refrigeration and air-
conditioning (DomRAC) units
2 Service and maintain Servicing and maintain HVC723338
domestic refrigeration and air- domestic refrigeration and
conditioning (DomRAC) units air-conditioning (DomRAC)
units
3 Troubleshoot and repair domestic Troubleshooting and repair HVC723339
refrigeration and air-conditioning domestic refrigeration and air-
(DomRAC) systems conditioning (DomRAC)
systems

HOW TO USE THIS COMPETENCY BASED LEARNING MATERIAL

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 2 of 178
Edwin P. Madarang
 Welcome to the Module Service and Maintain window type air-conditioning
unit and domestic/refrigeration system. This module contains training materials
and activities for you to complete.
The unit of competency “Service and Maintain window type air-conditioning
and domestic refrigeration system.” contains the knowledge and skills and attitudes
required for RAC SERVICING NC 1

You are required to go through a series of learning activities in order to complete

each learning outcome of the module. In each learning outcome are Learning
Experience, Information Sheets, Self-Checks, Answer Key, Task Sheet and Job
Sheets. Follow these activities on your own. If you have questions, don’t hesitate to
ask your facilitator for assistance.
The goal of this course is the development of practical skills. To gain these skills, you
must learn basic concepts and terminology. For the most part, you’ll get this
information from the Information Sheets and TESDA Website, www.tesda.gov.ph

This module was prepared to help you achieve the required competency in
“Service and Maintain window type air-conditioning unit and domestic
refrigeration system”. This will be the source of information for you to acquire
knowledge and skills in this particular competency dependently and at your own pace,
with minimum supervision or help from your instructor/facilitator.
Remember to:

• Work through all the information and complete the activities in each section.

• Read information sheets and complete the self-check. Suggested references are
included to supplement the materials provided in this module.

• Most probably your trainer will also be your supervisor or manager. He/she is there
to support you and show you the correct way to do things.
• You will be given plenty of opportunity to ask questions and practice on the job.
Make sure you practice your new skills during regular work shifts. This way you will
improve both your speed and memory and also your confidence.

• Use the Self-checks, Operation Sheets or Job Sheets at the end of each section to
test your own progress.

• When you feel confident that you have had sufficient practice, ask your Trainer to
evaluate you. The results of your evaluation will be recorded in your Record of
Achievement.

Date Developed: Document No.

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 MODULE CONTENT

QUALIFICATION : RAC SERVICING NC 1

UNIT OF COMPETENCY: Service and Maintain window type air-conditioning unit and
domestic refrigeration system.

MODULE TITLE: Servicing and Maintaining window type air-conditioning unit and
domestic refrigeration system.

INTRODUCTION:
This module covers the knowledge, skills and attitudes in providing
Servicing and Maintaining window type air-conditioning unit and domestic
refrigeration system. It includes clean air filter, repair evaporator, maintain motor
blades, service refrigerant circuit and electrical control and wiring.. It also includes,
information sheets, self-checks, job sheets, operation sheets and performance criteria
checklist.

LEARNING OUTCOMES:
At the end of this module you MUST be able to:
 Clean air filter
 Clean and repair evaporator and condensers
 Maintain motor blades
 Service refrigerant circuit
 Service electrical control and wiring.

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LEARNING OUTCOME #1 Clean air filter
CONTENTS:
 Classification of air filter
 Cleaning procedure
ASSESSMENT CRITERIA:
The learning outcome stated above is attained if you can demonstrate the
following:
1 Air filter is identified and removed following standard procedures
2. Filter is checked for damage and replaced if required in line with SOPs
3. Air filter is cleaned using the correct tools and cleaning procedures
4. Filter is replaced in accordance with filter specifications

CONDITION: Students/Trainees must be provided with the following:

1. WORKPLACE LOCATION:
Equipment
Computer
LCD
2. TOOLS, ACCESSORIES AND SUPPLIES
Equipment Tools
 R\R machine  Wrench set
 Nitrogen equipment  Tubing tools set
 Oxy acetylene  Pinch Off pliers
 Vacuum pump  File
 Screw driver set
 Service ratchet
Instruments  Soldering iron
 Multi-tester  Wire crimper
 Gauge Manifold  Pliers set
 Thermometer  Wire stripper
 Electric leak Detector  Crimping pliers
 Weighing scale
 Clamp ammeter
 Megger Personal Protective Devices
 Vacuum meter  Goggles
 Gloves
 Gas mask
Supplies and Materials  Safety shoes

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  Refrigerant  Working clothes
 Electrical wire
 Electrical tape
 Terminal end connector Learning Materials
 Access valve  LEs/CBLM on window AC &
 Copper tube Domestic Refrigeration
 Filter/drier, braze type  Text books/Manuals
 Silver rod  Catalogue
 Brazing flux  Brochure
 Rags  Work instructions
 Capillary tube
 Aluminum rod
 Soldering lead
 Wire harness tire
 Filter drier
 Flare fittings
 Refrigerant hose gasket
 Nitrogen gas
 Access valve cap
ASSESSMENT METHOD:
Written Test
Demonstration

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LEARNING EXPERIENCES

LEARNING OUTCOME NO. 1: Clean air filter

Learning Activities Special Instruction

1. Read information sheet # 2.1-1on  If you have some problem on the content of
Identifying / Classifying Air filters and the information sheet, don’t hesitate to
Proper Maintenance. approach your facilitator.
 If you feel that you are now knowledgeable
on the content of the information sheet, you
can now answer self-check provided in the
module.

 Compare your answer to the key. If you got

2. Answer the Self-Check #2.1-1. 100% correct answer on the self-check,
you can now move to the next information
sheet. If not review the information sheet
and go over the self-check again.

 Evaluate your own work using the

3. Perform Job sheet 2.1-1 on Cleaning Air performance criteria.
Filters and Proper Maintenance  Present your work to your trainer for
evaluation.
 Keep a copy for your work for the next
activity.

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 INFORMATION SHEET #2.1.1
AIR FILTERS

LEARNING OBJECTIVES: After reading this information sheet you should be able to:
a. identify different types of air filters
b. Clean air filters

INTRODUCTION
Preventive maintenance, proper service and troubleshooting play a big part in keeping
humidifying equipment operating efficiently. Cleaning the components that are in contact with
the water is the most important factor. In evaporative system, these minerals of water collect on
the media, on other moving parts and in the reservoir. In addition, algae, bacteria, and virus
growth can cause problems, even to the extent of blocking the output of the humidifier. The
reservoir should be drained regularly if possible and components, particularly the media type,
should be cleaned periodically.

DIFFERENT TYPES OF AIR FILTERS

FIBERGLASS FILTER MEDIA

This media may be purchased in bulk or in frames.

This material is usually an inch thick and coated with
a special non-drying, non-toxic adhesive on each
fiber. A filter material is designed so that it gets
progressively dense as the air passes through it.

Fiberglass filter media purchased in bulk.

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 FibergIass filter media purchased in a
frame.

Section of fiberglass media.

2. EXTENDED SURFACE AIR FILTERS

Some applications do not permit the use of fiberglass

as a filter media or require a higher air velocity than
fiberglass allows. Extended surface filters are after
made of non-woven cotton, producing air-cleaning
efficiencies of up to three (3) times greater than the
fiber glass. This type of filter is often used in computer
and electronic equipment rooms.

Extended surface air filters.

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3. STEEL WASHABLE AIR FILTERS

These filters are permanent and are washed rather

than replaced. They are usually used in commercial
applications such as in restaurants, hotels, and
schools.

A steel washable filter.

4. BAG-TYPE AIR FILTERS

This is another type of filter that produces greater

filtering efficiencies. These filters use fine fiberglass
media within the bags and remove microscopic
particles. These may be used in hospital operating
rooms, electronic equipment assembly rooms and
computer equipment rooms.

Bag-type filter

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SELF CHECK # 2.1.1
MATCHING TYPE

DIRECTION: For each statement below, write the letter corresponding to your answer on the
space provided

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This is another type of filter that produces greater A.
filtering efficiencies. These filters use fine
fiberglass media within the bags and remove STEEL WASHABLE AIR
microscopic particles. These may be used in FILTERS
hospital operating rooms, electronic equipment
assembly rooms and computer equipment rooms

These filters are permanent and are washed

rather than replaced. They are usually used in B.
commercial applications such as in restaurants,
hotels, and schools. EXTENDED SURFACE
AIR FILTERS
Some applications do not permit the use of
fiberglass as a filter media or require a higher air
velocity than fiberglass allows. Extended surface
filters are after made of non-woven cotton, C.
producing air-cleaning efficiencies of up to three
(3) times greater than the fiber glass. This type of BAG-TYPE AIR
filter is often used in computer and electronic FILTERS
equipment rooms.
This media may be purchased in bulk or in
frames. This material is usually an inch thick and
coated with a special non-drying, non-toxic
adhesive on each fiber. A filter material is D. FIBERGLASS
designed so that it gets progressively dense as FILTER MEDIA
the air passes through it.

Key answer of self check # 3.1-1

1. D
2. C
3. B
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 4. A

JOB SHEET#2.1.1

Cleaning Air Filter

PERFORMANCE OBJECTIVE : Given a cleaning tools and materials in refrigeration and
air-conditioning the trainee should be able to clean air filters.

SUPPLIES/MATERIALS , TOOLS AND Equipment:

EQUIPMENT:

Window-type air conditioning unit

Vacuum cleaner
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 Pressure washer
TOOLS:
Standard slot-type screwdriver
Philips screwdriver
Fin comb
Paint brush
MATERIALS:
Soap (detergent)
Rags

STEPS AND PROCEDURE:

Disconnect electrical power from window-type

air conditioning unit.

Note: Do not remove the power plug by pulling

by the cord.

Remove the front intake grill. Pull up the front

intake grill about 90 and slide it slightly to
the left to unhook the tabs.

CAUTION: Do not raise the front intake grill

higher than 90 to the unit to prevent damage.

Remove the air filter. Tilt up and pull out the air
filter by the holder.

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Clean the filters using a vacuum cleaner.

Note:
Turn off the unit and pull out the power plug.
Clean the filters once a month.

Rinse the filters under running water and dry

them completely. After drying re-fit them
correctly into their guides.

Attach the air filter to the front grill.

Slide the front intake grill slightly to the right to

reattach the tabs and then push it down to
close tightly.

ASSESSMENT METHOD:
A. 1. Demonstration with oral questioning

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PERFORMANCE CRITERIA

: Acceptability

Yes No

1 Air filter is identified and removed following standard procedures ______ ______

2. Filter is checked for damage and replaced if required in line with ______ ______
SOPs

3. Air filter is cleaned using the correct tools and cleaning procedures ______ ______

4. Filter is replaced in accordance with filter specifications ______ ______

Learning Outcome #2 : Wash evaporator and condenser coils

Assessment Criteria :

 Proper tools are selected in dismantling evaporator and condensing coils.

 High-pressure washer is used in cleaning evaporator and condensing coils.
 Cleaning agent or non- corrosive chemicals are used in cleaning
 Evaporator and condensing coils are checked for air brake
 Fin comb is used in strengthening coil fins.

Resources:

Equipment and materials

You should be provided with the following:

1. Air conditioning unit

2. Air filter
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 - Disposable
- Reusable
3. Personal Protective Equipment (PPE)
4. Service manual
5. Basic hand tools
- Set of screwdrivers
- Set of wrenches
6. High pressure washer
7. Cleaning agent
- Liquid soap
- Soap powder
8. Forms
- Job order
- Requisition Slip

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LEARNING EXPERIENCES

LEARNING OUTCOME NO. 2: Wash Evaporator and Condenser

Learning Activities SPECIAL INSTRUCTION

1. Read Information Sheet  If you have some problem on the content of

#1.2-1 Evaporator the information sheet, don’t hesitate to
approach your facilitator.
#1.2-2 Condenser  If you feel that you are now knowledgeable
#1.2-3 cleaning and Rinsing solvent on the content of the information sheet, you
can now answer self-check provided in the
module.

2 Answer Self-Check  Compare your answer to the key. If you got

100% correct answer on the self-check,
#1.2-1 Evaporator you can now move to the next information
#1.2-2 Condenser sheet. If not review the information sheet
and go over the self-check again.
#1.2-3 cleaning and Rinsing solvent
3. Perform Cleaning/Removing and/or  Evaluate your own work using the
Replacing the evaporator condenser coils. performance criteria.
Jobsheet  Present your work to your trainer for
evaluation.
# 1.2.1 Cleaning,removing/replacing
evaporator Keep a copy for your work for the next
activity.
#1.2-2 Cleaning Condenser

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 CLEANING/REMOVING AND/OR REPLACING THE
EVAPORATOR/CONDENSER COILS

INFORMATION SHEET #1.2-1

LEARNING OBJECTIVES: After reading this information sheet you should be able to:
a. identify different types/classification of evaporators
b. Clean evaporator

Introduction:
The Evaporator is the part of the low-pressure side of the refrigeration and air conditioning
system in which the low-pressure liquid refrigerant boils and evaporates. Here the liquid
refrigerant picks-up (absorbs) heat from a cooling medium and changes it into gas
(evaporation). The evaporator is commonly called freezer coil, cooling coil, or chiller.

Two Main Types of Evaporator

1. Dry or direct expansion type

2. Flooded type

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Dry or direct expansion evaporator is not actually
“dry” but has a refrigerant control device that admits
only enough liquid refrigerant to be completely
evaporated by the time it reaches the outlet of the
coil. All the refrigerants leave the coil in a dry state or
dry vapor. The feed for such evaporator may be either
at the top or the bottom.

Direct or dry expansion evaporator

Flooded evaporator recirculates the refrigerant by

using surge chamber or accumulator. The surge
chamber is a drum in which liquid enters from
metering device. The whole surface of the evaporator
coil is in contact with the liquid refrigerant under all
load condition.

Flooded type

CLASSIFICATION OF EVAPORATOR

STATIC

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Cold Plate

Shell

Forced Air

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Fin

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 EVAPORATOR LOCATION

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 INFORMATION SHEET #1.2-2

CONDENSER

LEARNING OBJECTIVES: After reading this information sheet you should be able to:
a. identify different types of condensers
b. Clean condensers

Refrigeration in real sense is simply moving heat from a place where it is not wanted to a place where it is not
objectionable. The condenser is a device used for removing heat from the refrigeration system. It is a component
which transfers the heat from the refrigeration system to a medium which has lower temperature than refrigerant
present in condensers; it can absorb and move heat to an ultimate disposal point. The condenser is the door
opening provided to transfer unwanted heat out of the refrigeration system. Air and water are the two basic media
in which condensers could reject their heats. These two are selected because they are usually available in
sufficient quantities and are cheap. They are also easy to handle and are not dangerous. Their normal temperature
range is also satisfactory for liquification of refrigerant.

TYPES OF CONDENSER

There are three types of condensers. The name of each type is determined by the condensing medium. An air-
cooled condenser uses air as the condensing medium; a water-cooled condenser, water and the evaporative
condenser, both air and water.

Major types of condensers

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CLASSIFICATION OF CONDENSER

STATIC

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 FORCED AIR

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 INFORMATION SHEET #1.2-3

IDENTIFYING CLEANING AND RINSING SOLVENTS

OBJECTIVES: After completing this Information Sheet, you should be able to:

- identify the various kinds of cleaning and rinsing solvents by getting 100% score in
the self-check.

EQUIPMENT, MATERIALS AND AIDS YOU WILL NEED:

QUANTITY UNIT DESCRIPTION

Kerosene
1 liter

1 liter Gasoline

1 piece Wire brush

1 piece Steel brush

Cloth

1 piece Refrigerant container

1 box Soap

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INTRODUCTION

A good cleaning material for refrigeration systems should be able to remove oil, grease and
sludge. The cleaning method to be followed must remove moisture and not injure the parts of
the unit or harm the user.

1. Cleaning and rinsing solvents come in various kinds

depending on the parts to be cleaned or rinsed. The
most common ones are soap and water, kerosene,
gasoline and carbon tetrachloride.

2. The refrigerator body and the compressor housing

may be cleaned by scrubbing the surface using
brush and washing it with water.

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3. Plastic parts should be cleaned gently with soft
bristles or cloth. Use water mixed with a few
milliliters of vinegar.

NOTE: Do not use gasoline or thinner in cleaning

plastics.

4. Soiled parts can easily be cleaned using kerosene

and rubbing the dirt off with a brush. Corroded metal
parts may be cleaned using a rust converter and a
steel brush.

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5. The inside of a compressor can easily be cleaned
using gasoline or kerosene.

NOTE: When using gasoline, keep away from open

flame or sparks to avoid explosion. Gasoline is
highly flammable.

6. Evaporators and capillary tubes are cleaned by

using liquid carbon tetrachloride. This may be
bought from local drugstores.

WARNING:

The American Standards Association cautions that

constant contact of this substance with the skin may
be toxic to the user. (The threshold limit for carbon
tetrachloride is placed at 10 parts per million at an
eight-hour exposure time).

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NOTE:

Carbon tetrachloride however, should never be

used in cleaning the refrigerator or air-conditioning
mechanism because it is toxic and harmful to the
skin and respiratory system.

7. Most servicing centers recommend the use of R-

123 for flushing the system contaminated by motor
burn-outs because it is non-toxic and non-
flammable. It does not also leave non-condensable
residues and has no reaction to electrical insulation.

Container with R 123

Dichlorotrifluoroethane

8. Most of the oil from coated pieces are removed by

using solvents. They are immersed into the solvent
usually mineral spirits placed in hooded and vented
containers.

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9. To remove grease or lubricants made from animal
or vegetable oils, soak the piece in alkaline solution
so that the oil will react with the alkali to form water
soluble soap compounds. This process is called
saponification.

10. If minerals cannot be removed by saponification

process, you may try the emulsification process -
the process by which solid are melted by mixing
them with liquids.

11. The steam cleaning method may also be tried. This

is done by exposing the piece to hot water or steam
so that the grease will turn into fluid and float to the
surface. Extra care should, however, be taken so
that the service technician will not suffer from burns.

12. Caustic solution cleaning is done by dissolving

caustic solution in hot water and rubbing the piece
with the hot solution to remove grease and oil.

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13. Nowadays, there are several cleaning fluids
available in the market. When using them read and
follow the manufacturer’s recommendations
carefully.

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 SELF-CHECK #1.2-1

CALL YOUR INSTRUCTOR who will guide you and check your work after doing the self-check
below. You have five minutes to finish this test.

Match column A with column B. Write the letter before each number.

Column A Column B

______ 1. Caustic solution cleaning a. carbon tetrachloride

______ 2. Steam cleaning b. for cleaning soiled pieces

______ 3. Solvent cleaning c. dissolving solids by mixing with

liquids

______ 4. Saponification d. soaking into alkaline solution

______ 5. Emulsification e. for flushing contaminated systems

______ 6. For cleaning evaporators and capillary f. for cleaning plastics

tubes

______ 7. Refrigerant 11 g. for cleaning body of refrigerator

______ 8. Water with vinegar h. for cleaning inside of compressor

______ 9. Kerosene i. for removing oil from coated pieces

by immersion

______ 10. Water j. removing grease and oil by

immersion in hot solution

k. exposing part to hot water or

steam to remove dirt

l. for cleaning body of refrigerator or

compressor

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 JOB SHEET #1.2-1

CLEANING, REMOVING AND/OR REPLACING THE EVAPORATOR

OBJECTIVES: After completing this Job Sheet, you should be able to:

- clean the evaporator heat exchanger surfaces;

- remove and repair an evaporator;

- pressure-wash a finned evaporator; and

- straighten bent fins.

EQUIPMENT, MATERIALS AND AIDS YOU WILL NEED:

QUANTITY UNIT DESCRIPTION

Sample evaporator available
1 piece

1 piece Paint brush

1 unit Tube cutter

1 piece Hacksaw

1 pail Soap and water solution

1 set Oxy-acetylene

1 piece Brazing rod

1 piece Clean rag

1 piece Leak tester

1 piece Sand paper (water proof)

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 1 unit Steam cleaner

INTRODUCTION

The inside and outside surfaces of the evaporator must be kept clean for good heat transfer. Air
or water being cooled must flow in and out of the evaporator efficiently. See illustration below.

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CLEANING THE EVAPORATOR SURFACES

1. Brush off dust or foreign materials with a paint

brush, as shown.

2. Blow compressed air to the evaporators to

remove dust and foreign materials.

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3. Isolate the parts to be opened from the rest of the
system.

4. Using soap and water, clean and dry the joints to

be opened.

5. As soon as the ends of the evaporator tubing is

opened, plug the openings using wood or cork.

Date Developed: Document No.

May 2011
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6. Polish the weld or clean the brazed joint with
sand paper.

7. Test for Leaks. If leak is detected, repeat brazing again.

8. For aluminum evaporators, repair with an

aluminum solder, aluminum braze, aluminum
weld or a special epoxy.

- Locate the leak.

- If necessary, refer to the L.E. on “Leak Testing”.

Date Developed: Document No.

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9. Discharge the refrigerant. If necessary, refer to
the L.E. on “Evacuating or Flushing the System”.

10. Clean the metal around the leak with a cloth or

brush.

11. Using a file/sandpaper, remove the hard surface

oxide.

Date Developed: Document No.

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12. Braze or weld the leak

NOTE:
If necessary, refer to the Learning Element on
“Soldering and Brazing”

13. Polish the weld or clean the brazed joints using

sandpaper.

14. Test for leaks. If a leak Is detected, repeat brazing again.

Date Developed: Document No.

May 2011
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15. Polish the weld or clean the brazed joints using
sandpaper.

PRESSURE WASHING THE FINNED EVAPORATOR

1. Dirt insulates the condenser, thus hampers the

heat transfer. The fins and coil of the condenser
must be clean so that the airflow through the coils
will not be insulated from the fin or plate area and
there will be efficient transfer of heat.

- The finned condenser can be cleaned by

compressed air, nitrogen or carbon dioxide. See
figure below for equipment to be used.

Date Developed: Document No.

May 2011
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2. Set the pressure regulator of the compressed air,
nitrogen or carbon dioxide at 6.90 kg/cm by
turning the pressure regulator valve handle
clockwise, as shown by the arrow in the picture.

3. Slowly work the spray up and down the fins.

4. Direct the spray nozzle so that it is parallel to the

fins. Do not spray at an angle to the fins because
they could be bent and may cause damage to the
coil.

5. Bring the spray nozzle up in a vertical angle with

the fins and then cross about 2.54 cm. Bring the
nozzle down and repeat the up and down
movement of the spray.

6. Keep repeating the spraying pattern until the entire coil is covered.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
7. If the compressed air, soap and water spray fail
to thoroughly clean the evaporator, a portable
steam cleaner may be used. (See figure below.)
The steam jet should be sprayed with the same
technique as the compressed gas and soap and
water cleaning. The fins may be bent slightly but
they can be easily straightened with wide-nosed
pliers.

STEPS IN USING PORTABLE STEAM CLEANER

1. Open gate valve of water source by turning

counter-clockwise, as shown.

2. Plug-in steam cleaner to run motor and pump, as

shown.

Date Developed: Document No.

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3. Position evaporator to be cleaned by putting on
top of 2 wooden blocks, as shown.

4. Point the nozzle of the steam to the evaporator

and press the switch to bring out the steam, as
shown.

5. Slowly move the nozzle upward and downward

moving sideways to other fins until all the
evaporator area is cleaned.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
STRAIGHTENING BENT FINS

Bent fins may be straightened using a fin comb or wide-nosed pliers, as shown below.

PROCEDURE

1. Insert the wide nose pliers to the bend fins.

2. Press the wide nose pliers slightly until you see

that bends are already straight.

3. Repeat steps one and two until bent fins are

straightened.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 SELF-CHECK #1.2-2

CALL YOUR INSTRUCTOR who will observe you clean, remove or replace an evaporator as
well as straighten the bent fins of an evaporator.

Acceptability
Instructor’s checklist
Yes No

1. Selection and preparation of tools to be used ______ ______

2. Choice of method to be followed ______ ______

3. Setting-up of the workplace, tools, and equipment ______ ______

4. Preparation of the workpiece ______ ______

5. Quality of brazed portion or weldments. - Is it leak proof? ______ ______

6. Thoroughness in cleaning finned evaporators ______ ______

7. Quality of repaired bent fins. Is it straight enough after the repair? ______ ______

8. Speed in completing the job. The job should be completed in 2 ______ ______
hours.

9. Observance of safety precautions. ______ ______

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 JOB SHEET #1.2-2 - CLEANING A CONDENSER

I. Tools and materials

A. Window-type air conditioner

B. Plastic bag

C. Degreasing solvent

D. Water hose

E. Spray nozzle

II. Procedure

1. Remove air conditioner from cabinet.

(CAUTION: Always ask for help when lifting heavy objects.)

2. Set air conditioner close to a floor drain or outside the room

3. Wrap the fan motor with a plastic bag.

(NOTE: Water may ruin the fan motor.)

4. Remove screws that hold the condenser to fan shroud.

5. Carefully swing condenser out (Figure 1)

Date Developed: Document No.

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 (CAUTION: Do not swing the condenser out
far enough to avoid kinking or breaking the
refrigerator lines.)

6. Spray degreasing solvent onto condenser.

7. Allow solvent time to work.

Figure 1

8. Attach water hose to hydrant.

(NOTE: If using hot water, be sure the hose is

designed for use with hot water.)

9. Attach spray nozzle to water hose.

10. Spray condenser with water (Figure 2). Figure 2

11. Tilt air conditioner sideways so that water will run out.

12. Remove plastic bag from fan motor.

13. Dry all electrical components with a shop towel.

14. Carefully move condenser back into proper position.

15. Replace screws which hold the condenser to the shroud.

16. Have instructor check.

17. Replace air conditioner in cabinet.

18. Clean up and put away tools and materials.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
Learning Outcome # 3 : Lubricate Fan Motor

Assessment Criteria:

 Fan motor is checked in line with standard operating procedures.

 Lubricant is selected according to manufacturer’s specification.

 Fan motor is lubricated without spillage in line with standard operating procedures.

Resources:

EQUIPMENT AND MATERIALS:

You should be provided with following:

1. Air conditioning Unit, window type

2. Lubricant
3. Oil
4. Grease
5. Cleaning agent
6. Rags
7. Soap powder
8. Sand paper

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 51 of 178
Edwin P. Madarang
LEARNING EXPERIENCES

LEARNING OUTCOME NO. 3: Lubricate Fan Motor

Learning Activities Special Instruction

1. Read the Information Sheet  If you have some problem on the content of
#1.3-1 Cleaning and replacing fan the information sheet, don’t hesitate to
motor blade approach your facilitator.
 If you feel that you are now knowledgeable
on the content of the information sheet, you
can now answer self-check provided in the
module.

 Compare your answer to the key. If you got

2. Do Self-Check #1.3-1 & 1.3-2 100% correct answer on the self-check,
you can now move to the next information
sheet. If not review the information sheet
and go over the self-check again.

 Evaluate your own work using the

3. Perform job sheet 1.3-1Identifying performance criteria.
terminal leads of 3 speed fan motor  Present your work to your trainer for
&1.3-2 Cleaning fan motor and fan evaluation.
blade  Keep a copy for your work for the next
activity.

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 52 of 178
Edwin P. Madarang
 INFORMATION SHEET #1.3-1

CLEANING AND REPLACING FAN MOTOR AND BLADE

OBJECTIVE: After completing this Learning Element, you should be able to:

- clean and service a fan motor and fan blade that will function similar to a new unit.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Fan motor and blade
1 unit

4 unit blower

4 liters Motor cleaner

1 unit Paint brush 25 mm. wide

1 piece Screwdriver (standard)

1 piece Pliers

1 piece Bearing extractor

1 set Allen key wrenches

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 53 of 178
Edwin P. Madarang
FANS

Fans are used extensively in air conditioning and refrigeration units for moving or circulating air
over air cooled condensers and evaporators coil. The function of a fan is to increase the
pressure of air which it handles by converting into pressure, the relative velocity of air with
respect to the blades at the entrance. Fans are often designated as booster, blowers or
exhausters. As considered here, a booster is a fan with ducts connected to both inlet and
discharge; a blower has discharge duct only and exhauster has an inlet duct only.

TYPES OF FANS

Fans are identified into two general groups:

1. Centrifugal – in which air flows radially through impeller.

Forward curved blade Backward inclined blade Radial blade

2. Axial flow – in which air flows axially through the impeller.

Date Developed: Document No.

May 2011
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 Propeller Fans

Sirroco Fans

Propeller fan with slinger ring for spatters or

“sling” that throws droplets of water onto the
hot condenser.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
ELECTRIC FAN MOTOR

An electric fan motor is a mechanical device that converts electric energy into mechanical
motion. In an electric motor, electricity is used to produce magnetism. The magnetism is used to
turn a shaft, and the turning shaft is used to do work.

Electric motors are the most popular and

common type used for providing mechanical
power for air conditioning and refrigeration
system. They are popular because they are
readily available with the use of electricity and
their motors are simple.

MAJOR PARTS OF ELECTRIC (FAN)

MOTOR

1. Frame – the part that holds everything

together. It includes the end bell, outside
enclosure and the bearing or bushing.
2. Stator – the stationary part of the motor. It
includes the field coils (winding).
3. Rotor (armature) – the revolving part of the
motor. It includes the shafting.

Date Developed: Document No.

May 2011
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 JOB SHEET #1.3-1

IDENTIFYING THE TERMINAL LEADS OF 3-SPEED FAN MOTOR USING A

VOM (Volt-Ohm Milliammeter)

OBJECTIVES: After completing this Job Sheet, you should be able to:

- identify the terminal leads of a 3-speed fan motor using a VOM (Volt-Ohm-
Milliammeter).

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Multimeter VOM (Volt-Ohm-
1 unit
Milliammeter)
3-Speed fan motor
1 unit
Plastic electric tape
1 roll
Paper
1 pc.
Pencil or ball pen
1 pc.

Date Developed: Document No.

May 2011
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Introduction:

Terminal leads of fan motors are identified by color-coding and by the resistances of the
windings. The colors of the terminal leads may fade, making them hard to identify. The terminal
leads may have to be identified by the resistances of the windings.

Steps in identifying the terminal leads of a 3-speed fan motor using.a VOM:

1. Label the terminal leads from 1 to 5 as shown in Figure 1. Use a masking tape.

Figure 1.

2. Make a table like the one shown TERMINALS RESISTANCE RANK

on the right to record the (OHMS)
resistances of the different
terminal lead combinations. 1 1&2

2 1&3

3 1&4

4 1&5

5 2&3

6 2&4
Date Developed: Document No.
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 7 2&5

8 3&4

9 3&5

10 4&5

3. Set the multimeter at R x 1. Measure and

record the resistances of the different
terminal leads. Use the table prepared in
Step 2.

NOTE:
Adjust first the VOM to zero reading before
taking any resistance reading.
Countercheck the values or resistances
(Figure 2).

Figure 2

Date Developed: Document No.

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4. Rank the readings from highest to lowest,
making the highest reading as rank 1 and
the lowest as rank. 10.

Figure 3 illustrates diagramatically the windings of a

3 -speed fan motor.

Figure 3: Windings of a 3-speed fan motor

Characteristics of the Windings

Terminal:

A and C - highest resistance

A and L - second to the highest

H and M - is equal to M and L

C and H - higher than H and M or M and L

Date Developed: Document No.

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5. The terminal lead found both on the highest (Rank 1) and second highest resistance (Rank
2) is the auxiliary terminal lead.

NOTE:

If there is no terminal lead found on both the highest and second highest resistance, check
the values by measuring the resistance of the terminal leads again.

a. With the auxiliary terminal lead now identified, the other terminal lead on the highest
reading (Rank I) is the COMMON terminal lead.

b. The other terminal lead on the second to the highest reading (Rank 2) is the LOW
terminal lead.

6. Using the LOW terminal lead now as the reference point, measure the resistance of the two
remaining terminal leads.

a. The one with the higher resistance is the HIGH terminal lead.

b. The other unidentified terminal is the MEDIUM terminal lead.

7. Using now the LOW terminal lead as the reference point, measure the resistance of the
other terminal leads.

NOTE:

If the terminal leads are identified correctly, they must follow the table below.

Terminals

L and A - highest resistance

L and C - second highest resistance

L and H - second lowest resistance

Date Developed: Document No.
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 L and N - lowest resistance

NOTE:

If the readings of the resistances do not follow the pattern above, repeat identifying the
terminal leads.

Assignment

After carefully studying the step-by-step procedures of identifying the terminal leads of a 3-
speed fan motor using a VOM (Volt-Ohm-Milliammeter), ask for the materials and tools from the
instructor. Practice the skills required until you have gained mastery.

Date Developed: Document No.

May 2011
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 SELF-CHECK #1.3-1

CALL YOUR INSTRUCTOR who will observe you perform the steps in identifying the terminal
leads of a 3-speed fan motor using a multimeter (VOM). He will also evaluate your performance
using the Instructor’s Checklist.

Acceptability
Instructor’s checklist
Yes No

1. Checked if terminal lead have labels. ______ ______

2. Checked if VOM is adjusted at zero adjustment. ______ ______

3. Checked if terminal leads are ranked correctly. ______ ______

4. Checked if terminals are ranked correctly. ______ ______

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 JOB SHEET #1.3-2

CLEANING FAN MOTOR AND FAN BLADE

INTRODUCTION

All fans that move air accumulates dirt particularly on the fan blades and motor. Such dirt
reduces the efficiency of the fan. To maintain proper operation of the fan, the dirt should be
removed regularly.

Steps in cleaning fan motor and fan blade:

1. Disconnect lead wires of the motor and

remove the fan blade from the motor shaft.

Date Developed: Document No.

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2. Remove the motor cradle bolts/screws
holding the fan motor.

3. Lift the motor up and out and proceed to

clean the fan motor and blade.

Date Developed: Document No.

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4. Remove dirt and grease from the housing
of the motor.

5. Check the sleeve bearings by moving the

shaft up and down. If the movement is
excessive, the bearings or shaft may be
defective.

6. Mark the end plates of the motor with a

permanent pen or a punch before
disassembling it.

7. Loosen and remove the end plate screws

and bolts.

Date Developed: Document No.

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8. Remove the end plate by prying it from the
casing without using excessive force.

9. Remove the rotor. Make sure that the

windings in the rotor and stator are not
damaged, dented or scratched.

10. Soak the stator windings in motor cleaner

for about 5 minutes.

Date Developed: Document No.

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11. Use a paint brush to remove dirt and
grease from the stator assembly.

12. Rinse the stator assembly with fresh

motor cleaner. Allow to dry.

13. If all the motor parts are found to be in good condition, you may then assemble the motor.

1. housing
2. plate
3. rotor
4. end plate
5. bolt
6. bolt

Date Developed: Document No.

May 2011
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Edwin P. Madarang
CLEANING FAN BLADE

1. Remove the surface dirt and grease from

the blade.

2. Apply cleaning solution to fan blades then

wait for about 5 minutes. Clean stubborn
spots with smooth sandpaper.

3. Rinse the fan blade in water.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
REMOVING AND REPLACING DEFECTIVE
SLEEVE BEARINGS

1. If the shaft can be moved vertically, it

indicates a worn bearing, a worn rotor
shaft, or a worn bearing housing.

NOTE: A loose rotor shaft may cause the rotor

to rub on the stator core and cause the
windings to overheat and short.

- A defective sleeve bearing

2. If the sleeve bearing is defective, then proceed as follows.

Date Developed: Document No.

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3. Remove the cup cover containing the
sleeve bearing.

4. Remove the lock washer of the sleeve

bearing.

5. Force the bearings out of end plates using

the proper bearing extractor.

6. Remove all retainers.

Date Developed: Document No.

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7. Place the new sleeve bearing on the
extractor and press the bearing into the
end plate.

8. Return the oil retainer, lock washer and the end cap then reassemble the motor.

REMEDYING EXCESSIVE SHAFT END

PLAY.

1. Disassemble fan motor.

2. Insert or add two fan shaft washers to both

shaft ends.

3. Assemble again and test if there is any

more shaft end play.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 SELF-CHECK #1.3-1

CALL YOUR INSTRUCTOR to ask you to carry out a number of exercises in fan blade and
motor repair. He will observe you and check you according to the criteria stated below. You
have 45 minutes to complete this exercise.

Acceptability
Instructor’s checklist
Yes No

1. Selection of instrument and materials ______ ______

2. Use of tools ______ ______

3. Detection of defective sleeve bearing ______ ______

4. Disassembling of fan blade and fan motor ______ ______

5. Assembling fan motor ______ ______

6. Cleaning of fan motor and blade ______ ______

7. Detection of excessive shaft end play ______ ______

8. Removing and replacing of defective sleeve bearing ______ ______

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 73 of 178
Edwin P. Madarang
Learning Outcome #4 : Inspect Electrical Control/Wiring

Assessment Criteria:

 Proper electrical tools and test instrument are used in checking power supply and
electrical controls and wiring conditions

 All electrical controls, wiring, power supply are checked and inspected

 Loose connections and other wiring defects are reported

 Defective controls and wiring are repaired / replaced in line with standard operating
procedures.

Resources:

Equipment and Materials:

You should be provided with the following:

1. Electrical tools and test instrument

2. Set of screwdrivers
3. Electrical pliers
4. Multitester
5. Clamp ammeter
6. Electrical wire
7. Electrical tapes
8. Window-type air conditioning unit
9. Refrigeration unit

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 74 of 178
Edwin P. Madarang
LEARNING EXPERIENCES

LEARNING OUTCOME NO. 4: Inspect Electrical Control/Wiring

Learning Activities Special Instruction

1. Read the Information Sheet  If you have some problem on the content of
#1.4-1 Characteristic of hermetic the information sheet, don’t hesitate to
compressor motor winding approach your facilitator.
 If you feel that you are now knowledgeable
#1.3.-2 Overload protector on the content of the information sheet, you
# 1.3-3 electrical control can now answer self-check provided in the
module.

 Compare your answer to the key. If you got

100% correct answer on the self-check,
you can now move to the next information
4. Do Self-Check sheet. If not review the information sheet
#1.4-1 Characteristic of hermetic and go over the self-check again.
compressor motor winding
 Evaluate your own work using the
#1.3.-2 Overload protector performance criteria.
# 1.3-3 electrical control  Present your work to your trainer for
evaluation.
 Keep a copy for your work for the next
activity.

5. Perform job sheet 1.4-1Checking

electrical connection and control

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 JOB SHEET #1.4-1

CHECKING ELECTRICAL CONNECTIONS AND CONTROLS

OBJECTIVES: After completing this Operation Sheet, you should be able to:

- check electrical connections for tightness; and

- check electrical controls for normal operations.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Multitester (UDM)
1 unit
Clamp-On Ammeter, 300 Amps.
1 unit
Screw drivers
1 set
Open-end wrenches
1 set

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 76 of 178
Edwin P. Madarang
CHECKING ELECTRICAL TIGHTNESS

INTRODUCTION:

Short, open and loose connections in a refrigeration electrical circuits are the primary causes of
failures and breakdown. An open circuit will render a refrigerator totally inoperative. A short
circuit will blow out the use while loose connections will cause intermittent operation. and most
probably a burned motor compressor. Checking of the different electrical components and
circuits is necessary to locate the trouble and select the remedial measures to be applied.

Steps in checking electrical tightness:

1. Compressor terminal block. Check the

terminals to see if the screws are
tightened properly by using the
appropriate wrench, as shown.

2. Check the plug connection for tightness by

using a screw driver.

CHECKING ELECTRICAL CONTROLS FOR NORMAL OPERATION

Date Developed: Document No.

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1. Continuity test is shown.
- If the tester registers an infinite reading,
it means motor winding is good.

- If no reading is indicated, the motor

winding is open.

Date Developed: Document No.

May 2011
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2. The thermostat continuity test is shown.

- At R x 1, no reading means thermostat

is good.

- At R x 5 or 10, with reading means

thermostat is good.

- At R x 5 or 10, slowly turn the tester

knob to zero if tester point does not
deflect and remains in maximum
reading, it means thermostat is open or
shorted.

3. The overload protector test is shown.

- If tester registers an infinite reading, it

means overload protector is good.

- If tester does not register any reading,

overload protector is open or shorted.

Date Developed: Document No.

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4. The starting relay test is as shown.

- If tester registers an infinite reading, it

means starting relay (overload
protector) is good.

- If tester does not register any reading,

starting relay (overload protector) is
open or shorted.

5. The motor compressor test is shown.

Date Developed: Document No.

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6. The clamp ammeter test is shown.

Date Developed: Document No.

May 2011
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CHECKING POR OPEN/SHORT (CONTINUITY TEST)

1. Set the multitester to range R x 1.

NOTE: Refer to L.E. “Using the

Multimeter/ VOM” if necessary.

2. Apply a teat prod to the tip of the plug of

the refrigerator.

3. If the circuit is open or shorted, no

resistance reading will be noted on the
tester, as shown.

Date Developed: Document No.

May 2011
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4. If the circuit is not open or shorted, a
resistance reading will be noted at the
tester dial.

CHECKING THE THERMOSTAT CONTROL

1. Connect the test prods to the terminal, as

shown.

2. A good thermostat control will register zero

or no resistance.

Date Developed: Document No.

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3. If resistance is registered on the tester dial
as shown, the thermostat is shorted and
will have to be replaced.

CHECKING THE OVERLOAD PROTECTOR

1. Connect the test prods to the terminals of

the overload protector, as shown.

2. A good overload protector should indicate a

zero reading.

Date Developed: Document No.

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3. If resistance is registered on the tester dial
as shown, the overload protector is shorted
and will have to be replaced.

CHECKING THE MOTOR COMPRESSOR

1. Connect the test prods to “C” common and

“R” running term, as shown.

- CR with continuity

- CS with continuity

- RS without continuity

2. A reading of between 10 to 50 ohms should

register.

Date Developed: Document No.

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3. Any part of the compressor terminals
should not indicate any resistance reading
with respect to the body chassis of the
compressor. If reading is registered, then it
is grounded.

AMMETER TEST

1. Plug-in the refrigerator, as shown.

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2. Clip the clamp ammeter to one side of the
line cord.

3. If ammeter reading is higher than the

normal ampere rating of the motor
compressor, the internal winding is shorted.
Rewind or replace the compressor motor.

Date Developed: Document No.

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 INFORMATION SHEET #1.4-1

OVERLOAD PROTECTOR: TYPES, PARTS AND OPERATING PRINCIPLES IN A

REFRIGERATING SYSTEM

OBJECTIVES: After completing this Operation Sheet, you should be able to:

- explain the operation of an overload protector; and

- identify the parts of an overload protector.

MATERIALS, AND AIDS YOU WILL NEED

- Charts
- Transparencies
- Trainer

Date Developed: Document No.

May 2011
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Edwin P. Madarang
INTRODUCTION

Overload protector is in series with the running and starting winding. Overload protector allows
an excessive current for a very short time (about 3 to 4 seconds - approximate time for the
motor to start. It will break the circuit of the high current flows lasts for any length of time (5
seconds or more) As shown in figure 1.

Figure 1. Wiring Diagram

A. External Overload Protector

An overload protector during normal and

overcurrent/over heating conditions as
shown in Figure 2.

Figure 2. Normal condition (contact close)

When there is a high rise in temperature,

copper expands more than steel, causing
warping (or bending) of the bimetal disc
which opens the overload contacts thus,
removing the motor from the circuit. When
the temperature goes down to normal
level, the bimetal disc returns to its normal
position and the contact points close. Figure 3. Over control/overheating
(contacts open)
Overload protector on normal and overheating
or overheating position.

Date Developed: Document No.

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Edwin P. Madarang
Basic Parts of an Overload Protector

1. Heater - safeguards the

compressor against the overcurrent.
It is in series with the contacts and
the motor windings (see Figures 2
and 3). When the motor is subjected
to a sustained overcurrent, the
current through the heater is high,
and the temperature of the heater
increases. This heats the bimetal
disc.

Figure 4. Parts of an overload protector.

2. Bimetal disc and contacts

Safeguards the compressor motor

against overheating. The bimetal is
positioned beside the heater and this
senses the temperature change in the
heater and compressor dome (or
housing). It opens or closes the
contacts depending on the
temperature condition of the motor.
Figure 5. Overload Protection

3. Terminals and pin connector

- enable the overload protector to be

electrically connected to the circuit.

4. Case - holds the other parts in place.

Also makes the installation of the
overload protector possible.

Date Developed: Document No.

May 2011
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B. Internal Overload Protector

Internal overload protector is mainly used

in hermetic motors. It is installed inside the
motor winding and protects the motor from
overheating. When the winding
temperature rises above safe limits, the
internal overload protector opens and
disconnects the motor windings from the
power source, preventing damage to the
motor.

Figure 6. Locations of internal overload protector

Figure 7. Internal overload protector

The contact points are made of fine silver for excellent conduction of current. The bimetal
strip (disc) responds to temperature in the motor windings and closes the circuit when the
temperature goes down to a safe value.

Date Developed: Document No.

May 2011
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 SELF-CHECK #1.4-1

A. Without looking back on the previous pages, answer the following questions on a piece of
paper:

1. What are the functions of an overload protector?

2. How does a bimetal disc open or close the circuit?

3. What is the purpose of the heater?

4. Differentiate an external overload protector from an internal overload protector

B. Below are the parts and an illustration of a overload protector. Identify the parts by writing
the corresponding number of each part in the circle provided in the illustration. When you
have completed the activity. CALL YOUR INSTRUCTOR.

Parts of an Overload Protector

_______________ Case _______________ Bimetal disc

_______________ Terminals _______________ Contact

_______________ Pin Connector _______________ Heater

Date Developed: Document No.

May 2011
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 INFORMATION SHEET #1.4-2

CHARACTERISTICS OF HERMETIC COMPRESSOR MOTOR WINDINGS

OBJECTIVE:

After completing this Information Sheet, you should be able to:

- discuss the characteristics of hermetic compressor motor windings.

SUPPORT MATERIALS:

This Learning Element may be supplemented with the following:

1. Charts about hermetic motor

2. Transparencies
3. Trainers or cut-out view of a hermetic compressor motor

TECHNICAL INFORMATION

Hermetic compressor motor employs two kinds of windings: the starting and running
windings. Figure 1 shows the position of windings in the stator of the motor. They are
positioned this way so that the magnetic force created by each winding complements each
other to create a higher torque or force.

Date Developed: Document No.

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 Figure 1. The rotor and stator of hermetic motor.
The section shows the position of the start and run windings.

The start winding is used only during the starting period, that is, when the running winding alone cannot
develop the needed torque (force) to start the compressor. A relay is used to remove the start winding from the
circuit when the motor reaches its full speed.

The windings are insulated from the stator and compressor dome as shown in Figure 1. A
low resistance across the compressor dome or body, and any of the terminals reveals grounded
windings.
The start winding has a smaller diameter wire and so it has a higher resistance compared to the run winding.
The run winding which is energized every time the compressor runs is made of heavy-duty wire of bigger diameter.

The table below shows the resistance of the winding, (see also Figure 2).

TERMINALS WINDINGS REMARKS

C&R START Lowest resistance

C&S RUN Medium resistance

S&R RUN & START Highest resistance

COMBINED

Figure 2. Diagram of Compressor

Motor Windings

Date Developed: Document No.

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 The sum of the resistances of the run
and start winding is the resistance across S
and R terminals. If the total or the individual
resistances of the run winding (C& R) and
start winding (C & S) is not equal to the S
and R reading. The windings are partially
shorted. If this happens, the compressor
should be replaced with a new one.

To cool the windings during operation, the

cool refrigerant vapor from the suction line
flows over, the motor windings. The
compressor oil also helps in the distribution Figure 3. Refrigerant vapor from the suction line
of heat to the different parts of the cools the windings. The oil distributes heat to all
compressor. Figure 3 illustrates these in parts and lubricates the moving parts of the entire
details. compressor.

At the start, the flow of current is very high, about two to four times than the running current.
This Initial high current is called “locked rotor amperage”. When the motor attains about 75% of
its rated speed, the start winding is removed automatically from the circuit. The run winding
alone drives the compressor. The current passing through the running winding is called the
“running current”.

NOTE: The compressor motor should not be allowed to operate at high current for more than
ten seconds. The windings will be burned and destroyed permanently.

Date Developed: Document No.

May 2011
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 SELF-CHECK #1.4-2

Without looking back at the previous page, answer the following questions briefly in a
separate answer sheet.

1. Which has the highest resistance, the run or the start winding?

2. How high is the starting current compared to the running current of a compressor motor?

Date Developed: Document No.

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 INFORMATION SHEET #1.4-3

ELECTRICAL CONTROL, CURRENT AND POTENTIAL RELAYS

OBJECTIVE: After completing this Information Sheet, you should be able to:

- identify an electric control and its function;

- identify a temperature control and its functions;
- describe the construction of current relays and magnetic switches and their
operations; and
- describe the construction and operation of potential relay, by answering the questions
in the Progress Check correctly.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Current relay
1 pc.
Potential relay
1 pc.
Schematic diagram of temperature
1 pc.
control switch
Wiring diagram illustrating motor
1 pc.
control

Date Developed: Document No.

May 2011
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Edwin P. Madarang
INTRODUCTION:

An electric control is a device that makes or breaks electrical circuits. It controls the flow of
refrigerant, changes the capacity of the compressor, provides automatic defrosting, and
transfers liquid from one portion of the system to another.

An electrical household refrigerator uses an overload safety control and a motor starting relay,
aside from other electric controls previously described.

The temperature control is used to automatically

start and stop the motor and compressor as
often as necessary to maintain the desired
temperature in the refrigerator.

HOW TEMPERATURE CONTROL OPERATES

Date Developed: Document No.

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1. A thermostatic bulb changed with volatile
liquid, as shown, helps in the detection of
any change in temperature.

2. This change in temperature is transmitted to

the bellows through the capillary tube, as
shown.

3. The gas pressure on the bellow causes the

bi-metal to expand or contract, as the case
may be, as shown.

4. This expansion or contraction causes the

bimetal to press against the spring, as
shown.

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5. The compression of springs causes the
contact point to close and start the motor
and compressor, as shown.

6. As the motor runs, the control bulb is cooled

and the pressure in the bellows is reduced.
The reduction of pressure allows the spring
to push the bimetal in opposite directions,
snapping the switch and stopping the motor.
The control bulb slowly warms up until the
motor starts again and the cycle is repeated.

Current relays and magnetic switches are

generally used on low torque smaller (H.P.)
motors. Shown below is the diagram of a
current relay switch.

Relay – current type

Shown below is a diagram of current relay and magnetic switch connection.

Date Developed: Document No.

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 Current Relay Connection

CURRENT RELAY AND MAGNETIC SWITCH OPERATION

1. Current relay and magnetic switch are

normally open, as shown.

Date Developed: Document No.

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2. This normally open contact closes
immediately when the motor is energized
by the surge of current which occurs at the
time of starting (see illustration at right).

3. When the motor speeds up, the current drops and the magnetic coil which is in the main
winding circuit releases the movable contact, disconnecting the starting winding, as shown.

Date Developed: Document No.

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4. POTENTIAL RELAYS are generally used on high torque capacitor motors. Shown below is
diagram of the parts of a potential relay.

Parts of Potential Relay

POTENTIAL RELAY CONNECTIONS

High starting torque motors 2 terminal overload potential relay

Date Developed: Document No.

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1. The contacts are normally closed, as
shown.

2. The coil is continuously connected to the

starting winding, as shown.

3. The coil opens the starting contact when a

predetermined voltage appears across it,
as shown.

Date Developed: Document No.

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4. The contacts remain open during normal
operation, due to the induced start winding
voltage, as shown.

5. Contact closes when the voltage across it

is cut or stopped.

Date Developed: Document No.

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 SELF-CHECK #1.4-4

Read the items carefully and answer each question correctly. Write only the letters on the space
provided.

_____ 1. The function of which is to disconnects the motor from the source when the motor
becomes overloaded

a. pressure control
b. thermostat
c. temperature control
d. overload protector

_____ 2. Which one is NOT an electric control?

a. float switches
b. relays
c. capacitor
d. thermostat

_____ 3. An automatic switching device that disconnects the starting winding after reaching its
three-fourth rated speed is called

a. relay
b. overload
c. thermostat
d. running capacitor

_____ 4. A relay generally used on low torque smaller H.P. motor.

a. potential
b. current
c. pilot
d. capacitor
Date Developed: Document No.
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_____ 5. A winding of the motor that is disconnected when the motor has reached its
equivalent value

a. running
b. common
c. starting
d. secondary

_____ 6. Current and potential relay has similarities except in

a. overload
b. compressor terminals
c. control
d. motor capacity

_____ 7. When the motor resumes its normal operation, this winding is the only one connected
to the circuit.

a. starting
b. running
c. secondary
d. common

_____ 8. A type of relay generally used on a high torque capacitor motor.

a. potential
b. current
c. pilot
d. hot wire

Date Developed: Document No.

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Edwin P. Madarang
 ANSWER KEY to SELF-CHECK #1.4-4

1. d

2. c

3. a

4. b

5. c

6. d

7. b

8. a

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 INFORMATION SHEET #1.4-3

CAPACITORS: TYPES AND FUNCTIONS IN A REFRIGERATING SYSTEM

OBJECTIVES:

After completing this Information Sheet, you should be able to:

- Enumerate and discuss the characteristics of capacitors used in refrigeration and air
conditioning; and

- Explain the functions of capacitors in a circuit.

SUPPORT MATERIALS

For more information, refer to the following support materials:

1. Trainer
2. Charts
3. Transparencies

TECHNICAL INFORMATION

A capacitor is a device used to store electricity. It is usually made of two aluminum foils
separated by insulating materials. Leads are attached to the plates. See Figure 1 for
details.

Date Developed: Document No.

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 Figure 1. Capacitor Construction

The basic function of a capacitor is to store electrical energy and release it when
needed. In refrigeration and air conditioning, it is used to help start motors to improve
their power factor.

All capacitors have two basic ratings the microfarad (mfd) rating and the voltage rating.
The microfarad rating identified the capacitor’s electrical storage capacity which is
capacitance, while the voltage rating identifies the maximum voltage that can be applied
across the plates.

In specifying capacitors, both capacitance and voltage ratings are given.

Capacitors may be connected to a line with a lower voltage but not to a line with a higher
voltage. This means that a capacitor with a 220 volt rating may be connected to a 110
volt circuit, but a capacitor with a 110 volt rating cannot be connected to a 220 volt line.

Figure 2A shows the two types of capacitors used in refrigeration and air conditioning,
the starting and the running capacitors. Sometimes, both of these capacitors are
enclosed together in single case (see Figure 2B).

Figure 2A. Starting capacitor Figure 2b. Running capacitor with fan capacitor

Date Developed: Document No.

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Starting Capacitor

Starting capacitors are intended for short and

infrequent compressor starts (see Figure 2A).
They are made of aluminum foil, paper and a
material in paste or liquid form called
electrolyte. The starting capacitor is connected
in series with the starting winding as shown in
Figure 3. Figure 3. Wiring diagram for start and run
capacitor

The starting capacitor is intended to give additional power to the motor during the starting
period. Because this power is not necessary after the motor has attained its normal operating
speed, the current is automatically cut off from the starting winding by the starting relay to which
the starting capacitor is connected in series.

Running Capacitor

This is a heavy duty type-oil filled capacitor. it is lower in microfarad rating than the starting
capacitor. (See Figure 2B). It remains in the circuit at all times during compressor operations,
(see Figure 3). It is constructed in such a way that heat does not build up excessively.

The running capacitor also increases the rotating force during the starting period and
improves the motor’s running efficiency. It also reduces the running amperage (current) by
increasing the power factor of the motor.

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 SELF-CHECK #1.4-4

Without looking back at the previous pages, answer the following questions briefly:

1. Explain the function of a starting capacitor.

2. Differentiate a starting capacitor from a running capacitor.

3. How are capacitors specified?

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 INFORMATION SHEET #1.4-4

THE THERMOSTAT

OBJECTIVES:

After completing this Information Sheet, you should be able to:

- state the function and operating principle of the thermostat;

- state the purpose of the range and differential adjustment;

- install the thermostat according to a diagram satisfying the instructor’s checklist in the
Progress Check; and

- describe the methods of adjusting the range and differential setting; and answer all
the items in the Self-Check correctly.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Screwdriver
1 piece
Thermostat
1 piece
Sample of a thermostat

Illustration of a thermostat

Date Developed: Document No.

May 2011
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INTRODUCTION

Most refrigerator manufacturers design their units to operate only for 8 to 14 hours a day. This is
done by means of a thermostat temperature actuated control.

FOUR TYPES OF SENSING ELEMENTS OR BULBS USED IN A THERMOSTAT

1. Sensing element with gas charged

temperature bellows.

2. Vapor pressure temperature bellows.

3. Liquid charged temperature response

diaphragm.

4. Capillary tube coil used as bulb.

5. The capillary tube is the one that contacts the sensing element and the operating
mechanism.

Date Developed: Document No.

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6. Copper has a greater coefficient of expansion than iron. This bimetal strip will bend as the
temperature changes. The bending action of the bimetal will open and close the contact
point in an electrical circuit. You will observe that when the bimetal is heated, it bends
upward and when cooled, it bends downward.

FUNCTIONS OF A THERMOSTAT

Date Developed: Document No.

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1. It starts the compressor driving motor.

2. It stops the compressor driving motor.

Date Developed: Document No.

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PRINCIPLES OF OPERATION

1. Any change in temperature will be sensed

by the sensing bulb.

2. The bellows will expand or contract

3. The bellows will push the bimetal.

4. The contact will be closed.

Date Developed: Document No.

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5. 13. When contact is made, the motor
compressor will run until such time that the
predetermined cooling temperature is
attained.

6. When the predetermined temperature is

attained, the sensing bulb senses the
temperature, the bellows contract, contact
is cut off and the compressor motor stops.

RANGE ADJUSTMENT

It is the difference between the cut-in and

cut-out temperatures.

Example: cut-in temp. = 30F

cut-out temp. 20F

The range is between 30F and 20F limit.

DIFFERENTIAL ADJUSTMENT

It is the difference in cut-in and cut-out

temperatures.

Example: cut-in temp. = 30F

cut-out temp. = 20F
differential = 10F

Date Developed: Document No.

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METHODS OF ADJUSTING THE RANGE SETTING

1. Turning the range adjusting screw

clockwise increases the spring tension and
raises the cut-in and cut-out temperatures.

2. Turning the range adjusting screw

counterclockwise decreases the spring
tension and lowers the cut-in and cut-out
temperatures.

METHODS OF ADJUSTING THE DIFFERENTIAL ADJUSTMENT

1. Turning the differential adjusting screw

clockwise causes the limit bar to move
towards the screw head, thereby
increasing the travel of pin B in the slot.
This increases the differential by lowering
the cut-out temperature.

Date Developed: Document No.

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2. Turning the differential adjusting screw
counter clockwise raises the cut-out
temperature and reduces the differential.

INSTALLING A THERMOSTAT

In installing the thermostat, manufacturers

always recommend that the sensing bulb
be mounted firmly in the evaporator
surface, as shown.

STEPS IN INSTALLING A THERMOSTAT

1. Clamp sensing bulb to the evaporator, as

shown.

Date Developed: Document No.

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2. Screw thermostat control into the
refrigerator cabinet, as shown.

3. Install cover, as shown.

Date Developed: Document No.

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 SELF-CHECK #1.4.5

A. Matching type. Match column A with column B by writing the answer on the space provided.

Column A Column B

______ 1. Sensing bulb a. part of a thermostat that gets in contact

with metal during an increase in
temperature

______ 2. Bellows b. part of thermostat that relays the

temperature to the bellows

______ 3. Bimetal c. it connects the sensing bulb and the

bellows.

______ 4. Copper d. a metal which has a greater coefficient of

expansion than iron

______ 5. Contact point e. the point where the flow is opened or

closed

______ 6. Evaporator f. part of the system where the sensing bulb

is mounted firmly

______ 7. Range adjustment g. the difference between cut-out and cut-in

temperature

______ 8. Differential adjustment h. change within limit

i. snap action

Date Developed: Document No.

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 ANSWER KEY to SELF-CHECK #11.4-5

A. 1. b

2. a

3. c

4. d

5. e

6. f

7. i

8. g

B. 1. yes

2. yes

3. yes

4. yes

5. yes

6. yes

Date Developed: Document No.

May 2011
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Edwin P. Madarang
 INFORMATION SHEET #1.4-5

TYPES AND OPERATING PRINCIPLES OF A DEFROST TIMER

OBJECTIVE:

After completing this Information Sheet, you should be able to:

1. Explain how a defrost timer operates.

2. Explain the importance of a defrost timer in a refrigerating system.

SUPPORT MATERIALS:

If necessary, refer to the following materials:

1. Charts

2. Transparencies

3. Trainer

TECHNICAL INFORMATION:

The most common method of defrosting a refrigerating system is to turn the system
“OFF” until all the frost in the evaporator/freezer melts, after which it is turned “ON” again
manually.

In systems where automatic defrosting is required, a defrost timer is used to shut the
system down, and to start it again when the unit is defrosted. These timers defrost the
refrigerating system for a fixed period of time at regular intervals of 12 or 24 hours,
depending on the specific requirements of the unit.

Date Developed: Document No.

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 Figure 1 shows a typical diagram of the electrical circuit used in an automatic defrost
refrigerator. During the defrosting process, the compressor is turned off and current flows into
the defrost heater which melts the frost.

Figures 2-A and 2-B show the commonly used defrost timers in refrigerators. Figure 2-C
illustrates the switching mechanism of a typical defrost timer. Defrost timers consists simply of a
synchronous motor driving a single-pole-double-throw switch (SPDT). The motor makes one
defrost cycle every 12 hours.

Figure 2-A. Parts of a defrost timer.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 125 of 178
Edwin P. Madarang
 Figure 2-C. Symbol of the defrost timer shown in
Figures 2-A & 2-B.
Figure 2-B. Another form of defrost timer.

HOW THE DEFROST TIMER OPERATES

During the refrigeration cycle, the defrost timer switches the compressor ON and the defrost
heater is turned off (Figure 3). After a specific length of time, the defrost heater is switched ON
automatically, (see Figure 4). The defrost heater, which is attached to the evaporators then
melts all the frost. The timer stays in the defrost position from 12 to 30 minutes depending on
the manufacturer’s specifications. After all the frost is melted, the defrost heater is turned OFF
and the compressor is again switched on.

Figure 3. Defrost timer in refrigeration position. Figure 4. Defrost timer in defrost position.

Another type of defrost timer is shown in Figure 5. The additional switch makes it possible
for the connection of other electrical components to be controlled by the defrost timer.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 126 of 178
Edwin P. Madarang
 Figure 5. Defrost timer with switches.

EVAPORATOR FAN CONTROLLED BY THE DEFROST TIMER

Figure 6 illustrates the wiring diagram of a refrigerator using an evaporator fan. As shown,
the fan is controlled by the defrost timer. When the timer is in defrost mode, the compressor and
the evaporator fan are removed from the circuit. The defrost heater melts all the frost, after
which the compressor is in operation for 5 minutes. The fan is not activated immediately so that
it will not circulate the hot air generated by the defrost heater (see Figure 7-9 for details).

Figure 6. Electrical circuit for delayed fan shut off during defrost.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 127 of 178
Edwin P. Madarang
 Figure 7. Defrost timer in refrigeration position. Figure 8. Defrost timer at start of defrost cycle.

Figure 9. Defrost timer near end of defrost cycle.

Figure 10. Defrost timer which only shuts off the
refrigerating unit. No defrost heater used. (Timer
on defrost position)

The same defrost timer can be used for several types of defrost control arrangements.
Figures 10 - 13 illustrate these variations as used by different manufacturers of automatic
defrost refrigerators.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 128 of 178
Edwin P. Madarang
 Figure 11. Defrost timer which turns on defrost Figure 12. Defrost timer which shuts off
heater as it shuts off the refrigerating unit. (Timer compressor and fan motor and turns on the defrost
on defrost position) heater. (Timer on defrost position)

In some refrigerators, the defrost timer

turns on a solenoid valve instead of a defrost
heater.

Figure 13. Defrost timer which shuts off the

compressor and fan motor and turns on two
defrost heaters. (Timer on defrost position)

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 129 of 178
Edwin P. Madarang
 SELF-CHECK #1.4-5

Without looking back at the previous pages, answer the following questions briefly.

1. What is the use of the defrost timer?

2. Sketch the electrical diagram of a defrost timer controlling the compressor and a defrost
heater.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 130 of 178
Edwin P. Madarang
 JOB SHEET #1.4-3

OPERATION OF A SEMI-AUTOMATIC DEFROST TIMER

OBJECTIVES:

After completing this Operation Sheet, you should be able to:

- explain the operation of a semi-automatic defrost refrigerator; and

- identify the electrical components of a semi-automatic defrost refrigerator

MATERIALS, AND AIDS YOU WILL NEED

Chart - Wiring diagram of a semi-automatic defrost refrigerator

Trainer – Semi-automatic defrost refrigerator

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 131 of 178
Edwin P. Madarang
 Too much time and effort are usually spent manually in defrosting a refrigerator. To defrost
the refrigerator it is turned off and is turned on again when all the frost have melted and
removed from the evaporator.

However, semi-automatic defrost refrigerators are defrosted by manually starting the defrost
unit but will automatically run normally when all the frost have melted.

Figure 1 shows the wiring

diagram of a semi-automatic
defrost refrigerator. It has two
controls: the thermostat and the
defrost control.

- The thermostat controls

the operation of the
compressor motor.

- The defrost control

operates the solenoid
valve.

Figure 1. Wiring diagram of a semi-automatic defrost refrigerator.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 132 of 178
Edwin P. Madarang
During normal operation, no current flows to the
solenoid valve so the valve is closed. Figure 2 shows a
refrigeration cycle. The refrigerant flows to the
condenser, to the capillary tube, and then, to the
evaporator where it does some cooling.

During the defrosting period, the compressor

runs continuously.

Figure 2. Refrigerating in refrigeration

cycle (Solenoid valve is close)

To defrost the system, the defrost control button is

pressed. Current flows to the solenoid valve so that the
valve opens. Figure 3 shows the system in defrost
position. The refrigerant from the compressor now flows
directly to the evaporator. The hot refrigerant from the
compressor melts the frost on the evaporator.

When all the frost are melted, the defrost control

automatically turns off the solenoid valve. The
refrigerant flows to the condenser. The system is now in
normal operation.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 133 of 178
Edwin P. Madarang
 Figure 3. Refrigeration system in defrost position
(Refrigerant flows through the tube with less
resistance))

Figure 4 shows a thermostat and a defrost control

combined. The thermostat has its own sensing bulb to
control the compressor motor. The defrost control also
has its own sensing bulb to control the solenoid valve.
The sensing bulb of the defrost control detects the
presence or absence of frost in the evaporator.

When the sensing bulb has detected that all the frost
are melted during the defrosting period, it cuts the flow
of current to the solenoid valve.

Figure 4. When frost accumulates in the

evaporator again, press the push button to defrost
it. When all the frost are melted, the refrigerator
automatically operates normally all over again.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 134 of 178
Edwin P. Madarang
 SELF-CHECK #1.4-5

Without looking back at the previous pages, answer the following questions. Write the letter
only of the correct answer in a separate answer sheet.

1. To defrost a semi-automatic defrost refrigerator, one must:

a. turn off the thermostat

b. press the defrost button
c. remove/unplug the unit
d. leave the door open

2. The defrost control operates the:

a. cabinet light
b. compressor motor
c. solenoid valve
d. starting relay

3. During the defrosting period, the solenoid valves are

a. opened
b. closed
c. turned on
d. turned off

4. Circuit Diagram

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 135 of 178
Edwin P. Madarang
 After completing this Learning Element, a set of tools and instruments will be provided for
you to execute a performance test. Your instructor will record your proficiency using the
checklist provided.

Acceptability
Instructor’s checklist
Yes No

1. Checked the wiring circuit ______ ______

2. Tested the thermostat control ______ ______

3. Identified the troubles of the overload protector ______ ______

4. Checked the motor windings ______ ______

5. Observed safety precautions ______ ______

6. Handled tools and equipment safely ______ ______

7. Measured the ampere rating of an operating motor compressor ______ ______

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 136 of 178
Edwin P. Madarang
Learning Outcome #5: Inspect Refrigerant Circuit

Assessment Criteria:

 All parts of refrigerant circuit are checked as per manufacturer’s manual / specifications.

 Refrigerant condition is accurately diagnosed and repaired.

 Completion of work is reported and recorded.

 Correct servicing and maintenance procedures are followed.

Resources:

EQUIPMENT AND MATERIALS:

You should provided with the following:

1. Window-type air conditioning unit

2. Refrigeration unit

3. Leak testing instrument

4. Refrigerant cylinder

5. Vacuum pump motor

6. Brazing equipment

7. Nitrogen gas cylinder

8. Service manuals
Date Developed: Document No.
May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 137 of 178
Edwin P. Madarang
LEARNING EXPERIENCES

LEARNING OUTCOME NO. 5: Inspect Refrigerant Circuit

Learning Activities Special Instruction

1. Read the Information Sheet  If you have some problem on the content of
#1.5-1 Window Type ai- the information sheet, don’t hesitate to
conditioning cycle approach your facilitator.
 If you feel that you are now knowledgeable
on the content of the information sheet, you
can now answer self-check provided in the
module.

 Compare your answer to the key. If you got

6. Do Self-Check #1.5-1Window Type AC 100% correct answer on the self-check,
cycle you can now move to the next information
sheet. If not review the information sheet
and go over the self-check again.

 Evaluate your own work using the

performance criteria.
7. Perform job sheet 1.5-1 Tracing  Present your work to your trainer for
refrigerant restriction &1.5-2 Connecting evaluation.
domestic refrigerator 1.5-3 connecting  Keep a copy for your work for the next
drinking fountain 1.5-4 connecting activity.
domestic ref ( frost type) 1.5-5
connecting window type air-conditioner
1.5-6 Pressurizing and leak testing
WAC

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 138 of 178
Edwin P. Madarang
 INFORMATION SHEET #1.5-1

WINDOW-TYPE AIR-CONDITIONING CYCLE

Checking Refrigerant Charge

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 139 of 178
Edwin P. Madarang
 Date Developed: Document No.
May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 140 of 178
Edwin P. Madarang
 JOB SHEET #1.5-1

TRACING REFRIGERANT PATH RESTRICTIONS

OBJECTIVE: After completing this Job Sheet, you should be able to:

- trace refrigerant path restrictions; and

- identify at least three causes of the restriction.

EQUIPMENT, MATERIALS, AND AIDS YOU WILL NEED

QUANTITY UNIT DESCRIPTION

Refrigeration unit
1
Pressure gauge
1
Adjustable wrench
1
Leak detector
1

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 141 of 178
Edwin P. Madarang
INTRODUCTION:

The piping transports the refrigerant from one component in the system to the next. A
restriction along the refrigerant line will show trouble in the system. After tracing and identifying
the cause of the restriction, repairs can be made to restore the proper operation of the system.

1. Connect refrigerant hose to the process

tube of the compressor, as shown.

2. Connect the pressure gauge to the rubber

hose, as shown

3. Check for leaks by using a halide leak

detector or by applying soap bubbles on
every fitting.

Refer to Learning Element “Detecting

Leaks” if necessary.

4. Start the unit by plugging, as shown.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 142 of 178
Edwin P. Madarang
5. Allow the unit to run for 30 minutes.

Observe and check which of the indications below occur during the operation of the unit.

1. At the start of operation, the unit runs

smoothly as if the system normally
functions. Restriction occurs or begins only
when the evaporator temperature reaches
freezing point.

2. When moisture inside the evaporator tubes

is frozen, it will expand and will cause
partial restriction. During partial restriction,
the pressure gage will indicate pressure
reading lower than the usual evaporator
pressure.

3. When complete restriction occurs, the

reading will indicate vacuum pressure. The
system will defrost.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 143 of 178
Edwin P. Madarang
4. At the start of operation, the pressure
gauge will indicate a pressure reading
lower than the usual evaporator pressure.
There is low temperature from the
condenser down to the filter drier. This is
caused by foreign matter inside tubes that
reduces the pressure of the refrigerant.

5. Frosty or freezing surface at any portion of

the line from discharge to filter drier
indicates restriction. If no frosty surface is
observed in the high-pressure side,
restriction is caused by the filter drier.

6. Special cases of restriction caused by

careless technicians include;

- damaged or pinched tubing, and

- refrigerant path blocked by melted

solder alloy that penetrated the joints.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 144 of 178
Edwin P. Madarang
7. Effects on system operation are:

At the start of operation, the pressure

gauge will indicate vacuum pressure
reading from pressures higher than
atmospheric down to vacuum pressure; low
temperature of the condenser down to filter
drier. The evaporator will not freeze but will
give a lower temperature.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 145 of 178
Edwin P. Madarang
 SELF-CHECK #1.5-1

Check which of the following indicates restrictions:

_____ 1. Frosty or freezing surface

_____ 2. Reading in the pressure gauge indicates vacuum pressure

_____ 3. Leak

_____ 4. Refrigerant path blocked by melted solder alloy

CALL YOUR INSTRUCTOR to ask you to perform a number of exercises in tracing

refrigerant path restriction. He will rate you according to the criteria stated in the instructor’s
checklist below.

Acceptability
Instructor’s checklist
Yes No

1. Connected refrigerant hose and gauge ______ ______

2. Pinpointed the location of the restriction ______ ______

3. Identified the cause of the restriction ______ ______

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 146 of 178
Edwin P. Madarang
 JOB SHEET #1.5-2

Connecting Domestic Refrigerator, Frost-Type

I. TOOLS, INSTRUMENT & MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper

B. INSTRUMENTS / EQUIPMENT
1. multi-tester
2. clamp ammeter
3. refrigerator frost type

C. MATERIALS
1. automotive wire
2. terminal end connectors
3. electrical tape

II. PROCEDURE

a. Prepare tools, instrument and materials.

b. Interpret electrical diagrams.

Date Developed: Document No.

May 2011
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(DOMRAC) NC II Develop by: Issued by: Page 147 of 178
Edwin P. Madarang
c. Test electrical parts and components for short open and ground.

1. compressor motor
2. thermostat
3. overload protector
4. starting relay
5. cabinet lamp
6. door switch
7. cabinet heater
8. cord and plug

d. Gather data: Measure load resistance.

e. Identify terminal leads out. LOAD ACTUAL RESISTANCE

f. Connecting refrigerator circuit.
Compressor
1. compressor circuit
Cabinet lamp
2. cabinet light circuit
3. heater circuit (if) Cabinet heater

g. Test electrical circuit connection for

short, open and ground.

Control position Reading should be Actual resistance

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 148 of 178
Edwin P. Madarang
 Off thermostat Infinity/heater (if)
Close door

Off thermostat Cabinet lamp

resistance
Open door

On thermostat Compressor
resistance
Close door

On thermostat Compressor
resistance
Open door

h. Measure line voltage and hook clamp ammeter.

NOTE: Unit voltage rating Input voltage Actual line

should be voltage
To avoid damage of
instrument, set selector
switch to higher range.

i. Measure line current

Unit current Full load No load Lock rotor

Start current Run current
rating ampere ampere ampere

NOTE:

Refer unit nameplate rating and table reference for refrigerator.

j. Energize and operate the unit, make sure it is not grounded.

Date Developed: Document No.
May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 149 of 178
Edwin P. Madarang
k. Turn off thermostat and unplug the unit after commissioning.

NOTE:

Do not operate compressor in high current to avoid burning the motor windings.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 150 of 178
Edwin P. Madarang
 JOB SHEET #1.5-2

Connecting Drinking Fountain

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper
4. Nut driver

B. INSTRUMENTS/EQUIPMENT
1. multi-tester
2. clamp ammeter

C. MATERIALS
1. automotive wire
2. terminal connectors
3. electrical tape

II. PROCEDURE

A. Prepare the electrical parts and components.

B. Test the electrical parts and components

1. compressor
2. condenser fan
3. thermostat
4. overload protector
5. power and light indicator
6. cord and plug

C. Gather data

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 151 of 178
Edwin P. Madarang
  Measure load resistance

Table 1. Measuring load resistance

Load Resistance

Compressor

Condenser fan motor

Power light indicator

D. Interpret Diagrams

E. Connect drinking fountain circuits.

1. Compressor circuit
2. Condenser fan motor circuit
3. Power indicator light circuit

F. Test circuit for short, open and grounded before energizing.

Table 2.

Control position Actual resistance

Off thermostat

On thermostat

G. Measure line voltage and hook up clamp ammeter

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 152 of 178
Edwin P. Madarang
 NOTE:
To avoid damage to the voltmeter, always set the selector knob to a higher range in
measuring unknown voltage and current.

Table 3. Measure line voltage.

Unit voltage rating Input voltage Actual voltage

should be

10%

H. Energize and operate the unit.

NOTE:
Turn off thermostat before plugging the unit.

I. Commissioning

Unit current Full load No load Lock rotor

Start current Run current
rating ampere ampere ampere

J. After commissioning, turn off thermostat and unplug the unit.

K. Return tools, instrument and materials to the tool room. Clean work areas.

NOTE:
Do not operate compressor motor in a high current to avoid burning the motor
windings.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 153 of 178
Edwin P. Madarang
 JOB SHEET #1.5-4

Connecting Domestic Refrigerator (No-Frost)

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. set of Pliers
2. set of screwdrivers
3. wire stripper
4. wrenches

B. INSTRUMENTS/EQUIPMENT
1. refrigerator unit, no-frost
2. multi-tester
3. clamp-ammeter

C. MATERIALS
1. automotive wire #16 AWG
2. terminal end connector, female
3. electrical tape

II. INTERPRET ELECTRICAL DIAGRAM

III. TEST ELECTRICAL PARTS FOR SHORT, OPEN AND GROUNDS

 Compressor
 Fan motor
 Defrost timer
 Defrost heater
 Thermostat
 Cabinet lamp/switches
 Cabinet heater

IV. MEASURE LOAD RESISTANCE

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 154 of 178
Edwin P. Madarang
Table 1.

Actual
LOAD V FLA
resistance

1. Compressor

2. Evaporator Fan motor

3. Defrost heater

4. Condenser F. M.

5. Cabinet lamp

6. Cabinet heater

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 155 of 178
Edwin P. Madarang
V. IDENTIFY & MARK TERMINAL LEADS OUT
 Compressor
 Condenser fan motor
 Evaporator fan motor
 Defrost heater
 Defrost timer
 Thermostat
 Lamp and switches

VI. CONNECT NO-FROST REFRIGERATOR CIRCUITS

 Compressor circuit
 Evaporator fan motor circuit
 Defrost circuit
 Cabinet light circuit
 Cabinet heater circuit

VII. TEST ELECTRIC CIRCUIT FOR SHORT, OPEN & GROUNDS

Reading Actual
Control Position Test Point
should be resistance

1. OFF Load line Infinity/cabinet

/ heater

2. ON Load line Compressor

3. Defrost Load line Defrost heater

ohm

VIII. MEASURE LINE VOLTAGE & HOOK CLAMP-AMMETER

NOTE:
Always set instruments to highest range in measuring unknown electrical quantities.

IX. ENERGIZE & OPERATE THE UNIT

NOTE:
Do not energize if circuit is shorted, open or grounded.
Date Developed: Document No.
May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 156 of 178
Edwin P. Madarang
X. COMMISSIONING/GATHER DATA

NAMEPLATE RATING ACTUAL READING

HP V FLA NLA LRA V A

XI. TURN-OFF CONTROL & UNPLUG UNIT

XII. RETURN TOOLS, INSTRUMENTS & MATERIALS TO THE TOOL ROOM

XIII. CLEAN WORK AREA

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 157 of 178
Edwin P. Madarang
X
JOB SHEET #1.5-5

Connecting Window-Type Air-Conditioner

I. TOOLS, INSTRUMENTS AND MATERIALS

A. TOOLS
1. Set of Pliers
2. Set of screwdrivers
3. Wire stripper
4. Soldering Iron
5. Wire crimper

B. INSTRUMENTS/EQUIPMENT
1. multi-tester
2. clamp ammeter

C. MATERIALS
1. automotive wire
2. terminal connectors
3. electrical tape
4. soldering lead
5. plastic tie

II. PROCEDURE
1. Prepare tools and materials.
2. Interpret air con electrical wiring diagrams.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 158 of 178
Edwin P. Madarang
X

3. Test electrical parts/components for short, open and ground.

3.1 Compressor 3.6 OLP
3.2 Air swing motor
3.3 Air swing switch 3.7 Fan motor
3.4 Starting relay 3.8 Thermostat
3.5 Cord and plug
3.9 Capacitor
3.10 A/C switch

NOTE:
Replace defective parts.
4. Identify compressor parts.

Data Terminal Arrangement

1-2= C=

1-3= S=

2-3= R=

5. Identify fan motor.

Data Plotting Method

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 159 of 178
Edwin P. Madarang
X
1-2= 2-4=

1-3= 2-5=

1-4= 3-4=

1-5= 3-5=

2-3= 4-5=

6. Identify air con switch terminal.

Switch Terminals
Position

NOTE: C – close contact

O – open contact

7. Connect air con circuit.

7.1 Fan motor circuit
7.2 Compressor circuit
7.3 Air swing circuit

NOTE: Do not energize if shorted, open or grounded. Call the instructor for assistance.

8. Test air con circuit connection for short, open and ground.

Switch Position Actual Actual Current

Resistance

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 160 of 178
Edwin P. Madarang
X

NOTE: Fan position – High resistance

Cool position – Low resistance
Off – Infinity
9. Measure line voltage and hook up clamp ammeter.

Actual Voltage Name Plate Voltage should be

voltage

10% nameplate

10. Measure line voltage and hook up clamp ammeter.

NOTE:
Turn off A/C switch first before energizing.

11. Measure line current and record reading at table above.

12. Turn off and unplug unit after commissioning.

13. Keep tools and materials to tool room and clean the work area.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 161 of 178
Edwin P. Madarang
 JOB SHEET #1.5-6
Pressurizing and Leak Testing (Window-Type Air-Conditioner)

I. PREPARATION OF TOOLS, INSTRUMENTS, EQUIPMENT, MATERIALS AND PERSONAL

SAFETY EQUIPMENT

A. TOOLS
1. Tube cutter
2. Mechanical pliers
3. Tube reamer
4. Service ratchet wrench
5. Swaging tools
6. File
7. Brush

B. INSTRUMENTS/EQUIPMENT
1. Nitrogen equipment
2. Gauge manifold
3. Oxy-acetylene
4. Window A/C unit

C. MATERIALS
1. Access valve
2. Silver rod
3. Silver brazing flux
4. Leak detecting fluid (soap solution)

D. SAFETY GADGETS
1. Goggles
2. Gloves

II. INFORMATION

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 162 of 178
Edwin P. Madarang
 Once the refrigerant has been removed from a system and the system has been
assembled or repaired, the system must be pressurized for leak testing.

Pressurizing - a process of charging dry nitrogen or refrigerant in a recommended

system pressure for leak testing.

Dry Nitrogen - used for pressurizing refrigerator and air conditioning mechanical system
for leak testing or sweeping system lines during certain soldering or brazing procedures.

Leak Testing - a process of determining leakage in the refrigeration and air conditioning
system.

METHODS OF LEAK TESTING

1. Using soap solutions

2. Using halide leak detector
3. Using electronic leak detector
III. PROCEDURES IN PRESSURE-TESTING OF A REFRIGERATION SYSTEM

1. Install service access valve to the suction line and discharge line

2. Conned gauge manifold hoses to the system, red hose for discharge service line and
yellow hose for the nitrogen regulator out port and dose gauge hand valves.

NOTE: Do not overtight the hose fittings (finger tight only) to prevent damage of hose 0
rings.

3. Open nitrogen tank service valve and regulate the pressure to a minimum of 50 psi and a
maximum of 150 psi.

4. Purge the air in center fittings of a yellow hose to remove air contaminants.

5. Open pressure gauge hand valve and pressurize the system of about 50 psi or until
indicates the recommended pressure for leak testing.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 163 of 178
Edwin P. Madarang
 NOTE: Pressurizing a system must be done gradually and keep the pressure at the
recommended level while leak testing.

6. Observe pressure reading for changes in 5 to 30 minutes and perform leak testing.

NOTE: A drop of pressure indicates leakage.

IV. LEAK TESTING WITH SOAP SOLUTIONS

After system has been pressurized with nitrogen use a soap solution for leak testing
electronic leak detector and halide leak detector wilt not response to nitrogen

Leak detecting fluid

 diluted household detergent
 kid bubble solution

V. PROCEDURE

1. Apply solution using soft brush or spray it on, start at the gauge set, and apply on the
system joints and fittings.
2. Look for leaks around all fittings and connectors, evaporator and condenser coils, leak
are exposed when bubble formed.
3. Mark leak locations so you can make needed repair.
4. Vent the nitrogen charge to the atmosphere and proceed to evacuation procedures if no
leakage is found.

VI. COMMISSIONING

Type of Unit Pressure (PSI) Pressure Diff.

(PSI)
before after

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 164 of 178
Edwin P. Madarang
 Definition of Terms

ELECTRICAL COMPONENTS AND MECHANICAL ACCESSORIES

Blower fan motor - an electrically operated motor which drives the condenser and evaporator
fan.

Compressor motor - is the prime mover of refrigerant pump and heart of the system which
circulate the refrigerant gas to create cycle.

Selector switch - provide the user to operate the air conditioning to different selling such as
fan, low cool , medium cool, or high cool.

Thermostat temperature actuated switch - which will automatically put-off or put on the
compressor operation.

Dual Capacitor - an electrical storage which correct the power factor of the compressor and
blower motor.

Power Supply cord - this will allow the air conditioner to take power from the convenience
outlet so that it is operable by the user.

Air filter - a fine mesh screen installed at the face of evaporator coil which is used to filter dust,
dirt and fumes before it pass across the evaporator coil.

Control panel cover - this protect electrical control assembly of the control panel.

Front grille - holds the filter in place and also provide a neat appearance of the air conditioner
when installed.

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 165 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency
HVAC/R NC II
Standard:

InterviewQuestioning/
Ways in which evidences will be collected:
(tick the column)

Demonstration
The evidence must show that the candidate …

*Identified and removed parts/ components of the window type air-

conditioning and refrigeration in accordance with standard X X
procedures
*Cleaned parts/components in accordance with standard procedures X X
* Checked and inspected all controls/wiring as per schematic diagram
X X
and in line with SOP
* Checked/inspected all parts of the refrigerant circuit are as per
X X
manufacturer’s manual specifications
Checked for damage in the air filter in line with standard operating
X X
procedures
Cleaned the worksite and kept safe in line with work instructions X X
*Demonstrated compliance with safety regulations applicable to
X X
worksite operations
*Selected and used appropriate processes, tools and equipment to
X X
carry out tasks
*Communicated effectively with others where applicable to ensure
X X
safe and effective work operations
*FoIlowed correct servicing and maintenance procedures X X

Note: *Critical aspects of competency

Prepared by: Date:

Instructor

Checked by: Date:

Supervisor

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 166 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (DEMONSTRATION)

Trainees name:
Traineers Name:
Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic
Refrigeration Units
Qualification: HVAC/R NC II
Date of Assessment:
Time of Assessment:
Instructions for Demonstration:
Instruction is based on the activity sheet.

Materials and Equipment

Air conditioner and a refrigerator
Tick () to show if evidence is
OBSERVATION
demonstrated
Yes No
During the demonstration of skills, did the candidate: ACTUAL
1.0 – 3.0 5.0
1. Replace the filter in accordance with filter specification?   
2. Clean the filter in accordance to standard?   
3. *Interpret the work instruction to determine the job requirements?   
4. Observe housekeeping?   
5. Observe quality of work?   
6. Follow technical specification from manufacturer’s manual?   
7. Observe work safety?   

The Trainees demonstration was:

Competent  Not Competent 

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 167 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Trainees name:
Unit of competency: Service and maintain window type air-conditioning/refrigeration unit
Competency standards: HVAC/R NC II
Competent response
Oral/Interview questions
Yes No

What is air-conditioning?
Why is there no cooling even if the evaporator is clean and the
condenser is unclean or vice-versa?
What precautions would you take in analyzing work instructions?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Traineers signature: Date

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 168 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency
HVAC/R NC II
Standard:

InterviewQuestioning/
Ways in which evidences will be collected:
(tick the column)

Demonstration
The evidence must show that the candidate …

*Identified and removed parts/ components of the window type air-

conditioning and refrigeration in accordance with standard X X
procedures
*Cleaned parts/components in accordance with standard procedures X X
* Checked and inspected all controls/wiring as per schematic diagram
X X
and in line with SOP
* Checked/inspected all parts of the refrigerant circuit as per
X X
manufacturer’s manual specifications
Checked evaporator and condenser for damage in line with standard
X X
operating procedures
Cleaned the worksite and keeping safe in line with work instructions X X
*Demonstrated compliance with safety regulations applicable to
X X
worksite operations
*Selected and used appropriate processes, tools and equipment to
X X
carry out tasks
*Communicated effectively with others where applicable to ensure
X X
safe and effective work operations
*FoIlowed correct servicing and maintenance procedures X X

Note: *Critical aspects of competency

Prepared by: Date:

Instructor

Checked by: Date:

Supervisor

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 169 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (DEMONSTRATION)

Trainees name:
Trainers Name:
Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic
Refrigeration Units
Qualification: HVAC/R NC II
Date of Assessment:
Time of Assessment:
Instructions for Demonstration:
Instruction is based on the activity sheet.

Materials and Equipment

Air conditioner and a refrigerator
Tick () to show if evidence is
OBSERVATION
demonstrated
Yes No
During the demonstration of skills, did the candidate: ACTUAL
1.0 – 3.0 5.0
1. Clean the evaporator and condenser in accordance with service
procedure?   
2. Use cleaning agent or non-corrosive chemical in cleaning and
maintaining the evaporator, condenser coil, plates and fins?   
3. Use high-pressure washer in cleaning evaporator/ condenser with
recommended pressure for cleaning?   
4. Observe housekeeping?   
5. Observe quality of work?   
6. Follow technical specification from manufacturer’s manual?   
7. Observe work safety?   

The Trainees demonstration was:

Competent  Not Competent 

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 170 of 178
Edwin P. Madarang
LO #3 Lubricate fan motor.

ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency
HVAC/R NC II
Standard:

InterviewQuestioning/
Ways in which evidences will be collected:
(tick the column)

Demonstration
The evidence must show that the candidate …

*Identified and removed parts/ components of the window type air-

conditioning and refrigeration in accordance with standard X X
procedures
*Cleaned parts/components in accordance with standard procedures X X
* Checked and inspected all controls/wiring as per schematic diagram
X X
and in line with SOP
* Checked/inspected all parts of the refrigerant circuit as per
X X
manufacturer’s manual specifications
Checked fan motor for damage in line with standard operating
X X
procedures
Cleaned the worksite and keeping safe in line with work instructions X X
*Demonstrated compliance with safety regulations applicable to
X X
worksite operations
*Selected and used appropriate processes, tools and equipment to
X X
carry out tasks
*Communicated effectively with others where applicable to ensure
X X
safe and effective work operations
*FoIlowed correct servicing and maintenance procedures X X

Note: *Critical aspects of competency

Prepared by: Date:

Instructor

Checked by: Date:

Supervisor

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 171 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (DEMONSTRATION)

Trainees name:
Trainers Name:
Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic
Refrigeration Units
Qualification: HVAC/R NC II
Date of Assessment:
Time of Assessment:
Instructions for Demonstration:
Instruction is based on the activity sheet.

Materials and Equipment

Air conditioner and a refrigerator
Tick () to show if evidence is
OBSERVATION
demonstrated
Yes No
During the demonstration of skills, did the candidate: ACTUAL
1.0 – 3.0 5.0
1. Clean the fan motor and blades in accordance with service
procedure?   
2. Used cleaning agent or non-corrosive chemical in cleaning and
maintaining the fan motor and blades?   
3. Demonstrate correct sequence in disassembling and
assembling?   
4. Observe housekeeping?   
5. Observe quality of work?   
6. Follow technical specifications from manufacturer’s manual?   
7. Observe work safety?   

The Trainnees demonstration was:

Competent  Not Competent 

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 172 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Trainees name:
Unit of competency: Service and maintain window type air-conditioning/refrigeration unit
Competency standards: HVAC/R NC II
Competent response
Oral/Interview questions
Yes No

Explain the functions of the fan motor in the air-conditioner.

What is the probable cause of cooling failure, even if the evaporator
and condenser are clean?
What precautions would you take in analyzing work instructions?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Trainers signature: Date

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 173 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency
HVAC/R NC II
Standard:

InterviewQuestioning/
Ways in which evidences will be collected:
(tick the column)

Demonstration
The evidence must show that the candidate …

*Identified and removed parts/ components of the window type air-

conditioning and refrigeration in accordance with standard X X
procedures
*Cleaned parts/components in accordance with standard procedures X X
* Checked and inspected all controls/wiring are as per schematic
X X
diagram and in line with SOP
* Checked/inspected all parts of the refrigerant circuit as per
X X
manufacturer’s manual specifications
Checked electrical control for damage in line with standard operating
X X
procedures
Cleaned the worksite and keeping safe in line with work instructions X X
*Demonstrated compliance with safety regulations applicable to
X X
worksite operations
*Selected and used appropriate processes, tools and equipment to
X X
carry out tasks
*Communicated effectively with others where applicable to ensure
X X
safe and effective work operations
*FoIlowed correct servicing and maintenance procedures X X

Note: *Critical aspects of competency

Prepared by: Date:

Instructor

Checked by: Date:

Supervisor

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 174 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (DEMONSTRATION)

Trainees name:
Trainers Name:
Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic
Refrigeration Units
Qualification: HVAC/R NC II
Date of Assessment:
Time of Assessment:
Instructions for Demonstration:
Instruction is based on the activity sheet.

Materials and Equipment

Air conditioner and a refrigerator
Tick () to show if evidence is
OBSERVATION
demonstrated
Yes No
During the demonstration of skills, did the candidate: ACTUAL
1.0 – 3.0 5.0
1. Service the electrical control and wiring in accordance with
service procedure?   
2. *Select and use appropriate processes, tools and equipment to
carry out tasks?   
3. *Demonstrate compliance with safety regulations applicable to
working operations?   
4. Observe housekeeping?   
5. Observe quality of work?   
6. Follow technical specification from manufacturer’s manual?   
7. Observe work safety?   

The Trainees demonstration was:

Competent  Not Competent 

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 175 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Trainees name:
Unit of competency: Service and maintain window type air-conditioning/refrigeration unit
Competency standards: HVAC/R NC II
Competent response
Oral/Interview questions
Yes No

What are the different types of compressor?

How do you test voltages in the circuit?

How do you test resistance in the circuit?

What instrument is used in measuring AC circuit?

What precautions would you take in analyzing work instructions?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Trainers signature: Date

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 176 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (EVIDENCE PLAN)

Competency
HVAC/R NC II
Standard:

InterviewQuestioning/
Ways in which evidences will be collected:
(tick the column)

Demonstration
The evidence must show that the candidate …

*Identified and removed parts/ components of the window type air-

conditioning and refrigeration in accordance with standard X X
procedures
*Cleaned parts/components in accordance with standard procedures X X
* Checked and inspected all controls/wiring as per schematic diagram
X X
and in line with SOP
* Checked/inspected all parts of the refrigerant circuit as per
X X
manufacturer’s manual specifications
Checked refrigerant circuit for damage in line with standard operating
X X
procedures
Cleaned the worksite and keeping safe slate in line with work
X X
instructions
*Demonstrated compliance with safety regulations applicable to
X X
worksite operations
*Selected and used appropriate processes, tools and equipment to
X X
carry out tasks
*Communicated effectively with others where applicable to ensure
X X
safe and effective work operations
*FoIlowed correct servicing and maintenance procedures X X

Note: *Critical aspects of competency

Prepared by: Date:

Instructor

Checked by: Date:

Supervisor

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 177 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (DEMONSTRATION)

Trainees name:
Facilitators Name:
Competency Assessment Title: Service and Maintain Window-Type Air-Conditioning/Domestic
Refrigeration Units
Qualification: HVAC/R NC II
Date of Assessment:
Time of Assessment:
Instructions for Demonstration:
Instruction is based on the activity sheet.

Materials and Equipment

Air conditioner and a refrigerator
Tick () to show if evidence is
OBSERVATION
demonstrated
Yes No
During the demonstration of skills, did the candidate: ACTUAL
1.0 – 3.0 5.0
1. *Identified and removed parts/components of the window type air-
conditioning and refrigeration in accordance with standard   
procedures.
2. *Select and used appropriate processes, tools and equipment to
carry out tasks?   
3. *Check/inspect all parts of the refrigerant circuit as per
manufacturer’s manual specifications.   
4. Observe housekeeping?   
5. Observe quality of work?   
6. Follow technical specification from manufacturer’s manual?   
7. Observe work safety?   

The Trainees demonstration was:

Competent  Not Competent 

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 178 of 178
Edwin P. Madarang
ASSESSMENT INSTRUMENT (QUESTIONING/INTERVIEW)

Trainees name:
Unit of competency: Service and maintain window type air-conditioning/refrigeration unit
Competency standards: HVAC/R NC II
Competent response
Oral/Interview questions
Yes No
After vacuuming the system, what will you do to the system if you
want to go home?
Name the main component of the refrigeration system.

What is the importance of vacuuming the system?

What would you do if you do not have a refrigerant identifier for R-12
refrigerant and what will be your alternative to identify the refrigerant?
Explain the functions of the main components of the refrigeration
system.
What alternatives would you consider if do if you do not have an
acetylene gas tank to perform brazing?

How would you make yourself safe at all times?

Feedback to candidate:

Acceptable answers are:

1. [insert suggested answers to questions]

Traineers signature: Date

Date Developed: Document No.

May 2011
RAC SERVICING
(DOMRAC) NC II Develop by: Issued by: Page 179 of 178
Edwin P. Madarang
 PERFORMANCE TEST

Trainees Name: Date:

Test Attempt
st
Competency: Service and Maintain Window-Type Air Conditioning/ 1 2nd 3rd
Domestic Refrigeration Units

Directions: OVERALL EVALUATION

Level
CALL YOUR INSTRUCTOR. PERFORMANCE LEVELS
Achieved
Ask him/her to assess your
performance in the following 4 – Can perform this skill without supervision and with initiative
critical task and performance and adaptability to problem situations.
criteria below.
3 – Can perform this skill satisfactorily without assistance or
supervision.

You will be rate based on the 2 – Can perform this skill satisfactorily but requires some
overall evaluation on the right assistance and/or supervision.
side.
1 – Can perform parts of this skill satisfactorily, but requires
considerable assistance and/or supervision.

Instructor will initial the level achieved.

PERFORMANCE STANDARDS
For acceptable achievement, all items should receive a “Yes” or “N/A” Yes No N/A
response.

1. Identified and classified air filter used in window-type air-conditioning.

2. Air filter is checked for damage and replace if required in line with
standard operating procedures.
3. Air filter is cleaned using appropriate cleaning agent and tool.

4. Air filter is replaced in accordance with standard operating procedures.

5. Proper tools are selected and used in dismantling evaporator and
condensing coils.
6. High-pressure washer is used in cleaning evaporator/ condensing
coils.
7. Cleaning agent or non-corrosive chemical is used in cleaning
evaporator and condensing coils are checked for brake.
8. Fin comb is used in straightening coil fins.

9. Fan motor is checked in line with standard operating procedures.

10. Lubricant is selected according to manufacturer’s specification.
11. Fan motor is lubricated with no spillage in line with standard operating
procedures.
12. Proper electrical tools and test instruments are used in checking power
supply and electrical controls and wiring conditions.
13. All electrical controls, wiring power supply are checked and inspected.

14. Loose connections are other defects are reported.

15. Defective controls and wiring are repaired/replaced in line with
standard operating procedures.
16. All parts of refrigerant circuit are checked as per manufacturer’s
manual/specifications.
17. Refrigerant circuit condition accurately diagnosed and repaired.

18. Completion is reported and recorded.

19. Correct servicing and maintenance procedures are followed.