Centrifugal Liquid Chillers

Operations and Maintenance Supersedes: 160.78-O1 (820) Form: 160.78-O1 (521)

YMC2 Model A
with OptiView™ Control Center

8.1415 in

R-134a

Issue Date:
May 19, 2021
 Form 160.78-O1
Issue date: 05/19/2021

Important!
Read before proceeding!
General safety guidelines
This equipment is a relatively complicated apparatus. which it is situated, as well as severe personal injury or
During installation, operation maintenance or service, death to themselves and people at the site.
individuals may be exposed to certain components or
conditions including, but not limited to: refrigerants, This document is intended for use by owner-authorized
materials under pressure, rotating components, and rigging, installation, and operating/service personnel. It
both high and low voltage. Each of these items has the is expected that these individuals possess independent
potential, if misused or handled improperly, to cause training that will enable them to perform their assigned
bodily injury or death. It is the obligation and respon- tasks properly and safely. It is essential that, prior to
sibility of operating/service personnel to identify and performing any task on this equipment, this individual
recognize these inherent hazards, protect themselves, shall have read and understood the on-product labels,
and proceed safely in completing their tasks. Failure this document and any referenced materials. This in-
to comply with any of these requirements could result dividual shall also be familiar with and comply with
in serious damage to the equipment and the property in all applicable industry and governmental standards and
regulations pertaining to the task in question.

Safety symbols
The following symbols are used in this document to alert the reader to specific situations:

Indicates a possible hazardous situation Identifies a hazard which could lead to

which will result in death or serious injury damage to the machine, damage to other
if proper care is not taken. equipment and/or environmental pollu-
tion if proper care is not taken or instruc-
tions and are not followed.

Indicates a potentially hazardous situa- Highlights additional information useful

tion which will result in possible injuries to the technician in completing the work
or damage to equipment if proper care is being performed properly.
not taken.

External wiring, unless specified as an optional connection in the manufacturer’s product line, is not
to be connected inside the control cabinet. Devices such as relays, switches, transducers and controls
and any external wiring must not be installed inside the micro panel. All wiring must be in accor-
dance with Johnson Controls’ published specifications and must be performed only by a qualified
electrician. Johnson Controls will NOT be responsible for damage/problems resulting from improper
connections to the controls or application of improper control signals. Failure to follow this warn-
ing will void the manufacturer’s warranty and cause serious damage to property or personal injury.
Ensure power is removed from the input side of the VSD at all times when the chiller is under vacuum
(less than atmospheric pressure). The VSD maintains voltage to ground on the motor when the chiller
is off while voltage is available to the VSD. Insulating properties in the motor are reduced in vacuum
and may not insulate this voltage sufficiently.

2 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Changeability of this document

In complying with Johnson Controls’ policy for con- It is the responsibility of rigging, lifting, and operating/
tinuous product improvement, the information con- service personnel to verify the applicability of these
tained in this document is subject to change without documents to the equipment. If there is any question
notice. Johnson Controls makes no commitment to regarding the applicability of these documents, rig-
update or provide current information automatically ging, lifting, and operating/service personnel should
to the manual or product owner. Updated manuals, if verify whether the equipment has been modified and
applicable, can be obtained by contacting the nearest if current literature is available from the owner of the
Johnson Controls Service office or accessing the John- equipment prior to performing any work on the chiller.
son Controls Knowledge Exchange website at https://
docs.johnsoncontrols.com/chillers/.

Revision notes
Revisions made to this document are indicated in the following table. These revisions are to technical information,
and any other changes in spelling, grammar, or formatting are not included.

Affected pages Description

24 Replaced maintenance requirements table with maintenance inspections section.

Associated literature

Manual description Form number

YMC2 Installation 160.78-N1
YMC2 Unit Reassembly 160.78-N2
YMC2 Centrifugal Chiller Long Term Storage 50.20-NM5
YMC2 Field Connections 160.78-PW1
YMC2 Unit Wiring and Field Control Modifications 160.78-PW2
YMC2 Unit Renewal Parts 160.78-RP1
YMC2 OptiViewTM Contol Center Operation Manual 160.78-O2
OptiSpeedTM VSD Model HYP744 Renewal Parts 160.78-RP3

Conditioned based maintenance

Traditional chiller maintenance is based upon assumed Planned Service Agreement that leverages real time
and generalized conditions. In lieu of the traditional and historical data, delivering performance reporting,
maintenance program, a Johnson Controls YORK corrective actions required and data enabled guidance
Conditioned Based Maintenance (CBM) program can for optimal operation and lifecycle assurance. The pro-
be substituted. This CBM service plan is built around gram will include fault detection diagnostics, operation
the specific needs for the chiller, operating conditions, code statistics, performance based algorithms and ad-
and annualized impact realized by the chiller. Your lo- vance rules based rationale delivered by the Johnson
cal Johnson Controls Branch can propose a customized Controls Connected Equipment Portal.

JOHNSON CONTROLS 3
 Form 160.78-O1
Issue date: 05/19/2021

System nomenclature
Y M C 2 - S 0756 A A
YORK Mod level
Magnetic bearing Refrigerant R-134a
Centrifugal chiller Capacity in kW
S = Single stage
T = Two stage

Compressor nomenclature
M1 B - 197 F A A
Motor Gas path revision level
Motor design level Impeller design revision level
Impeller tip diameter (mm)
Rotation
F = Forward
R = Reverse

Vessel nomenclature
E A 25 14 271 B R 1 1 F C R
Inlet from front view
Vessel
R = Right
E = Evaporator
L = Left
C = Condenser
Heat exchanger mod level Waterbox type
C = Compact
Nominal inside diameter (inches)
M = Marine
Nominal length (feet) Water connection type
Marketing tube number F = Flanges
Tube code G = Grooved Standard
B = 3/4 in. Code 1 A = Victaulic AGS
C = 3/4 in. Code 2 Number of passes
D = 3/4 in. Code 3 Vessel refrigerant pressure code Water side pressure code
E = 3/4 in. Code 4 R = Code 180 1 = 150 psi
2 = 1 in. Code 1 S = Code 235 3 = 300 psi
3 = 1 in. Code 2 T = Code 300
4 = 1 in. Code 3 U = Code 350
5 = 1 in. Code 4 V = Code 400

Variable speed drive nomenclature

HYP 744 X H 15 D - 40
Hyper 40 = 380 V 60 Hz
50 = 400 V 50 Hz
Amps
46 = 460 V 60 Hz
X = Factory mount 68 = 415 V 50 Hz
R = Retrofit model
D = Disconnect switch
H = YMC2 chiller B = Circuit breaker
Liquid DWP
15 = 150 psi
30 = 300 psi

4 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Table of contents

SECTION 1 - SYSTEM FUNDAMENTALS.............................................................................................................7

System components.......................................................................................................................................... 7
Compressor..............................................................................................................................................7
Motor........................................................................................................................................................7
Heat exchangers......................................................................................................................................8
Evaporator................................................................................................................................................8
Condenser................................................................................................................................................8
Waterboxes..............................................................................................................................................8
Refrigerant flow control............................................................................................................................8
Optional service isolation valves.............................................................................................................. 8
Optional hot gas bypass...........................................................................................................................8
OptiViewTM Control Center........................................................................................................................8
Variable speed drive.................................................................................................................................9
System operation description............................................................................................................................ 9
Capacity control................................................................................................................................................. 9

SECTION 2 - SYSTEM OPERATING PROCEDURES........................................................................................13

Pre-starting...................................................................................................................................................... 13
Start-up............................................................................................................................................................ 13
Chiller operation.............................................................................................................................................. 13
Condenser water temperature control............................................................................................................. 13
Operating logs................................................................................................................................................. 13
Operating inspections...................................................................................................................................... 14
Daily.......................................................................................................................................................14
Weekly....................................................................................................................................................15
Monthly...................................................................................................................................................15
Semi-annually (or more often as required)............................................................................................. 15
Annually (more often if necessary)......................................................................................................... 15
Need for maintenance or service.................................................................................................................... 15
Stopping the system........................................................................................................................................ 15
Prolonged shutdown........................................................................................................................................ 15

SECTION 3 - MAINTENANCE..............................................................................................................................17
Renewal parts................................................................................................................................................. 17
Checking system for leaks.............................................................................................................................. 17
Leak testing during operation................................................................................................................. 17
Conducting R-22 pressure test........................................................................................................................ 17
Vacuum testing................................................................................................................................................ 18
Vacuum dehydration........................................................................................................................................ 19
Operation................................................................................................................................................19
Refrigerant charging........................................................................................................................................ 20
Checking the refrigerant charge during unit shutdown.................................................................................... 20
Handling refrigerant for dismantling and repairs............................................................................................. 21
Megging the motor.......................................................................................................................................... 21
Condensers and evaporators.......................................................................................................................... 21
General...................................................................................................................................................21
Chemical water treatment......................................................................................................................21
Cleaning evaporator and condenser tubes............................................................................................ 21

JOHNSON CONTROLS 5
 Form 160.78-O1
Issue date: 05/19/2021

Table of contents (cont'd)

Tube fouling............................................................................................................................................21
Tube cleaning procedures......................................................................................................................22
Acid cleaning of tubes............................................................................................................................22
Testing for evaporator and condenser tube leaks.................................................................................. 22
Compressor..................................................................................................................................................... 23
Electrical controls............................................................................................................................................ 23
Maintenance inspections for YORK YMC2 chillers...........................................................................................24
Daily.......................................................................................................................................................24
Weekly....................................................................................................................................................24
Monthly (or more often as required)....................................................................................................... 24
Annually (more often if necessary)......................................................................................................... 24

SECTION 4 - TROUBLESHOOTING....................................................................................................................25

List of figures

FIGURE 1 - YMC2 chiller components���������������������������������������������������������������������������������������������������������������������� 7

FIGURE 2 - Compressor prerotation vanes��������������������������������������������������������������������������������������������������������������9
FIGURE 3 - Refrigerant flow-through chiller����������������������������������������������������������������������������������������������������������� 11
FIGURE 4 - Liquid chiller log sheets�����������������������������������������������������������������������������������������������������������������������14
FIGURE 5 - Evacuation of chiller����������������������������������������������������������������������������������������������������������������������������17
FIGURE 6 - Saturation curve����������������������������������������������������������������������������������������������������������������������������������19

List of tables

TABLE 1 - System pressures���������������������������������������������������������������������������������������������������������������������������������18

TABLE 2 - Refrigerant charge��������������������������������������������������������������������������������������������������������������������������������20
TABLE 3 - Operation analysis chart�����������������������������������������������������������������������������������������������������������������������25
TABLE 4 - SI metric conversion�����������������������������������������������������������������������������������������������������������������������������27

6 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Section 1 - System fundamentals 1

TRANSFORMERS VSD PANEL

DIRECT-DRIVE
OPTIVIEW MOTOR
CONTROL COMPRESSOR
PANEL
MAGNETIC BEARING
CONTROLLER

CONDENSER
LIFTING
OPENINGS (4)
VSD
COOLANT
PIPING

LD14022
EVAPORATOR

COMPACT
WATER SIGHT
BOXES GLASS

Figure 1 - YMC2 chiller components

System components
The YORK Model YMC2 Centrifugal Liquid Chiller The motor includes angular contact ball bearings only
is completely factory-packaged including evaporator, for control of the rotor during shutdown after rotation
condenser, compressor, motor, OptiViewTM Control is stopped or during shutdown due to loss of power to
Center, and all interconnecting unit piping and wiring. the magnetic bearings.
See Figure 1.
The bearing control center maintains proper shaft posi-
Compressor tion in the magnetic bearings and counts events where
the touchdown ball bearings may have been contacted
The compressor is a single-stage centrifugal type pow- during shaft rotation to alert the operation where a bear-
ered by a hermetic electric motor, on a common shaft ing check may be necessary. The condition of the touch-
with a cast aluminum, fully shrouded impeller. The im- down bearings can be assessed by qualified service tech-
peller is designed for balanced thrust and is dynamically nicians electronically without opening the unit.
balanced and over-speed tested. The compressor model
number includes gas path revision level at the end of the Ensure power is removed from the input
model string. Gas path revision level A includes pre-ro- side of the VSD at all times when the
tation vanes. Gas path revisions B has fixed inlet vanes. chiller is under vacuum (less than atmo-
spheric pressure). The VSD maintains
Motor voltage to ground on the motor when the
chiller is off while voltage is available to
The compressor motor is a hermetic permanent magnet
the VSD. Insulating properties in the mo-
high speed design with magnetic bearings. The com-
tor are reduced in vacuum and may not
pressor impeller is overhung from the end of the motor
insulate this voltage sufficiently.
shaft and has no bearings of it's own.

JOHNSON CONTROLS 7
 Form 160.78-O1
Section 1 - System fundamentals
Issue date: 05/19/2021

Heat exchangers
Evaporator and condenser shells are fabricated from must be entered at chiller commissioning by a qualified
rolled carbon steel plates with fusion welded seams. service technician. Only a qualified service technician
Heat exchanger tubes are internally enhanced type. may modify these settings.

Evaporator While the chiller is shut down, the orifice will be pre
positioned to anticipate run. When the chiller is started,
The evaporator is a shell and tube, hybrid falling film,
if actual level is less than the level setpoint, a linearly
and flooded type heat exchanger. A distributor trough
increasing ramp is applied to the level setpoint. This
provides uniform distribution of refrigerant over tubes
ramp causes the setpoint to go from the initial refriger-
in the falling film section. Residual refrigerant floods
ant level to the programmed setpoint over a program-
the tubes in the lower section. Suction baffles are locat-
mable period of time. If the actual level is greater than
ed above the tube bundle to prevent liquid refrigerant
the setpoint upon run, there is no pulldown period,
carryover into the compressor. A 2 in. liquid level sight
it immediately begins to control to the programmed
glass is located on the side of the shell to aid in deter-
setpoint.
mining proper refrigerant charge. The evaporator shell
contains dual refrigerant relief valves unless condenser While the chiller is running, the refrigerant level is nor-
isolation is installed. mally controlled to the level setpoint.

Condenser Optional service isolation valves

The condenser is a shell and tube type, with a discharge If your chiller is equipped with optional service iso-
gas baffle to prevent direct high velocity impingement lation valves on the discharge and liquid line, these
on the tubes. A separate subcooler is located in the con- valves must remain open during operation. These
denser to enhance performance. Dual refrigerant relief valves are used for isolating the refrigerant charge in
valves are located on condenser shells and optional re- either the evaporator or condenser to allow service ac-
frigerant isolation valves are available. cess to the system. A refrigerant pump-out unit will be
required to isolate the refrigerant.
Waterboxes
The removable compact waterboxes are fabricated Isolation of the refrigerant in this system
of steel. The design working pressure is 150 psig must be performed by a qualified service
(1034 kPa) and the boxes are tested at 225 psig technician.
(1551 kPa). Integral steel water baffles provide the
required pass arrangements. Stub-out water nozzle
connections with Victaulic grooves are welded to the
waterboxes. These nozzle connections are suitable for Optional hot gas bypass
Victaulic couplings, welding or flanges, and are capped
for shipment. Plugged 3/4 in. drain and vent connec- Hot gas bypass is optional and is used to provide great-
tions are provided in each waterbox. Optional marine er turndown than otherwise available for load and head
waterboxes are available. conditions. The OptiViewTM Control Center will auto-
matically modulate the hot gas valve open and closed
Refrigerant flow control as required. Adjustment of the hot gas control valve
must only be performed by a qualified service techni-
Refrigerant flow to the evaporator is controlled by a
cian.
variable orifice. See Figure 3.
A level sensor senses the refrigerant level in the con- OptiViewTM Control Center
denser and outputs an analog voltage to the Microboard The OptiViewTM Control Center is factory-mounted,
that represents this level (0% = empty; 100% = full). wired and tested. The electronic panel automatically
Under program control, the Microboard modulates a controls the operation of the unit in meeting system
variable orifice to control the condenser refrigerant cooling requirements while minimizing energy usage.
level to a programmed setpoint. Other setpoints affect For detailed information on the Control Center, refer
the control sensitivity and response. These setpoints to the YMC2 OptiViewTM Control Center Operations
Manual (Form 160.78-O2).

8 JOHNSON CONTROLS
Form 160.78-O1
Section 1 - System fundamentals
Issue date: 05/19/2021

Variable speed drive

1
A variable speed drive (VSD) is factory packaged with The major components of a chiller are selected to
the chiller. It is designed to vary the compressor motor handle the required refrigerant flow at full load design
speed by controlling the frequency and voltage of the conditions. However, most systems will be called upon
electrical power to the motor. The drive also supplies DC to deliver full load capacity for only a relatively small
power to the motor magnetic bearing controller for bear- part of the time the unit is in operation. A means exists
ing operation. Operational information is contained in to modulate capacity for other loads.
the OptiSpeed VSD Service Manual (Form 160.78-M3).
The control logic automatically adjusts motor speed and Capacity control
compressor prerotation vane position for maximum part The speed at which the compressor rotates establishes
load efficiency by analyzing information fed to it by the pressure differential that the chiller can operate
sensors located throughout the chiller. against. As speed is reduced, the chiller power use is
reduced. At reduced capacity requirements where con-
System operation description
denser pressure is also reduced, the motor speed is re-
The YORK Model YMC2 Chiller is commonly applied duced as much as possible while maintaining chilled
to large air conditioning systems, but may be used on water temperature and sufficient pressure differen-
other applications. The chiller consists of a hermetic tial. When the speed cannot be further reduced due to
motor mounted to a compressor, condenser, evapora- pressure difference required for the specified leaving
tor, and variable flow control. chilled water temperature setting and available cooling
to the condenser, other means to reduce refrigerant gas
The chiller is controlled by a modern state-of-the-art flow are used to manage capacity. Compressor models
Microcomputer Control Center that monitors its opera- M1B-197FAA and M1B-205FAA use a device called
tion. The Control Center is programmed by the opera- prerotation vanes (PRV) at the entrance to the impeller
tor to suit job specifications. Automatic timed start-ups to reduce capacity. See Figure 2.
and shutdowns are also programmable to suit night-
time, weekends, and holidays. The operating status,
temperatures, pressures, and other information perti-
nent to operation of the chiller are automatically dis-
played and read on a graphic display. Other displays
can be observed by pressing the keys as labeled on the
Control Center. The chiller with the OptiViewTM Con-
trol Center is compatible with the VSD.
In operation, a liquid (water or brine to be chilled)
flows through the evaporator, where boiling refrigerant
absorbs heat from the liquid. The chilled liquid is then
piped to fan coil units or other air conditioning terminal
units, where it flows through finned coils, absorbing
heat from the air. The warmed liquid is then returned to
the chiller to complete the chilled liquid circuit.
The refrigerant vapor, which is produced by the boil-
ing action in the evaporator, flows to the compressor
where the rotating impeller increases its pressure and
temperature and discharges it into the condenser. Wa-
ter flowing through the condenser tubes absorbs heat
from the refrigerant vapor, causing it to condense. The
condenser water is supplied to the chiller from an ex-
ternal source, usually a cooling tower. The condensed
refrigerant drains from the condenser into the liquid LD15000
return line, where the variable orifice meters the flow Figure 2 - Compressor prerotation vanes
of liquid refrigerant to the evaporator to complete the
refrigerant circuit.

JOHNSON CONTROLS 9
 Form 160.78-O1
Section 1 - System fundamentals
Issue date: 05/19/2021

Regardless of chiller compressor model, the chiller A final optional means to reduce capacity called hot
also has a mechanism called variable geometry dif- gas bypass (HGBP) is available regardless of compres-
fuser (VGD) at the exit of the impeller that was de- sor model. When selected for an application, HGBP is
signed to mitigate stall. Stall is an effect caused by used to re-circulate some refrigerant through the com-
slow refrigerant gas passing through the compressor at pressor without using it for cooling the chilled liquid.
reduced flow rates needed for low capacity operation. Although this does not reduce power consumption, it
Compressor models with gas path revision level B do greatly reduces the capacity of the chiller for maxi-
not have operating prerotation vanes, but use the VGD mum turndown.
also as a capacity control device instead.
The YMC2 uses these mechanisms in a controlled or-
der to maintain best efficiency.

10 JOHNSON CONTROLS
Form 160.78-O1
Section 1 - System fundamentals
Issue date: 05/19/2021

ROTOR COOLING
GAS VENT
(M1B-197FAA and M1B-205FAA)
COMPRESSOR

HOT GAS
BYPASS VALVE

PRE-ROTATION
VANES
DISCHARGE (M1B-197FAA and M1B-205FAA)
CHECK VALVE

SUCTION

DISCHARGE

LIQUID LEVEL
ISOLATION VALVE
VALVE

CONDENSER EVAPORATOR

SUCTION
BAFFLE

SUB-COOLER

ISOLATION LIQUID COOLING

VALVE FOR MOTOR STATOR

Figure 3 - Refrigerant flow-through chiller

JOHNSON CONTROLS 11
 Form 160.78-O1
Issue date: 05/19/2021

THIS PAGE INTENTIONALLY LEFT BLANK.

12 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Section 2 - System operating procedures

Pre-starting Chiller operation 2

Before starting the chiller, observe the OptiViewTM Con- The chiller will vary capacity to maintain the leaving
trol Center. Refer to the YMC2 OptiViewTM Control Cen- chilled liquid temperature setpoint by a specific se-
ter Operations Manual (Form 160.78-O2). Make sure quencing of optional hot gas bypass, pre-rotation vanes
that the display reads "SYSTEM READY TO START". or variable geometry diffuser, and compressor speed.

Vent any air from the chiller waterboxes Throughout capacity control, the compressor speed is
before starting the water pumps. Failure maintained above the minimum required for the pre-
to do so will result in pass baffle damage. vailing head condition, to avoid surge. Otherwise, the
device maintaining capacity is controlled by a pro-
portional-integral-derivative control based on leaving
chiller liquid temperature. Pressure and motor current
overrides also apply as necessary to maintain operating
Start-up limits.
1. If the chilled water pump is manually operated,
Condenser water temperature control
start the pump. The Control Center will not al-
low the chiller to start unless chilled liquid flow The YORK YMC2 chiller is designed to use less power
is established through the unit. If the chilled liq- by taking advantage of lower than design temperatures
uid pump is wired to the Microcomputer Control that are naturally produced by cooling towers through-
Center the pump will automatically start, there- out the operating year. Exact control of condenser wa-
fore, this step is not necessary. ter such as a cooling tower bypass, is not necessary for
most installations. The minimum entering condenser
2. To start the chiller, press the RUN key on the
water temperature for other full and part-load condi-
Home Screen on the display panel.
tions is provided by the following equation:
For display messages and information pertaining
where:
to the operation of the OptiView™ Control Cen-
ter, refer to the YMC2 OptiViewTM Control Center ECWT = entering condensing water temperature
Operations Manual (Form 160.78-O2). LCHWT = leaving chilled water temperature

Any malfunctions which occur during At initial startup, entering condensing water tempera-
SHUTDOWN are also displayed. ture may be as much as 30°F (16.66°C) colder than the
standby chilled water temperature.
Min ECWT = LCHWT -30°F (16.66°C)

At start-up, the entering condenser water temperature

The coolant temperature inside any JCI-supplied liq- may be as much as 30°F (16.66°C) colder than the
uid-cooled motor starter must be maintained above the standby return chilled water temperature. Cooling tow-
dewpoint temperature in the equipment room to prevent er fan cycling will normally provide adequate control
condensing water vapor inside the starter cabinet. There- of the entering condenser water temperature on most
fore, an additional temperature-controlled throttle valve installations.
is needed in the flow path for the starter heat exchanger
to regulate cooling above the equipment room dewpoint Operating logs
for applications using cooling sources other than evapo- A permanent daily record of system operating condi-
rative air-exchange methods, such as wells, bodies of tions (temperatures and pressures) recorded at regular
water, and chilled water. The temperature control valve intervals throughout each 24-hour operating period
should be the type to open on increasing drive coolant should be kept. Automatic data logging is possible by
temperature, fail-closed, and set for a temperature above connecting the optional printer and programming the
dewpoint. It can be requested as factory-supplied on a DATA LOGGER function. An optional status printer
chiller order by special quotation.

JOHNSON CONTROLS 13
 Form 160.78-O1
Section 2 - System operating procedures
Issue date: 05/19/2021

is available for this purpose. Figure 4 shows an ex- Daily

ample log sheet used by Johnson Controls Personnel 1. Check OptiView™ Control Center displays.
for recording test data on chiller systems. Log sheets
are available in pads of 50 sheets and can be obtained 2. Check entering and leaving condenser water pres-
through the nearest Johnson Controls office. Request sure and temperatures for comparison with job
the YMC2 Centrifugal Liquid Chiller Log Sheets (Form design conditions. Condenser water temperatures
160.78-MR1). can be checked on the SYSTEM Screen.

An accurate record of readings serves as a valuable ref- 3. Check the entering and leaving chilled liquid tem-
erence for operating the system. Readings taken when peratures and evaporator pressure for compari-
a system is newly installed will establish normal condi- son with job design conditions on the SYSTEM
tions with which to compare later readings. Screen.

For example, an increase in condenser approach tem- 4. Check the condenser saturation temperature on
perature (condenser temperature minus leaving con- the SYSTEM Screen.. This temperature is based
denser water temperature) may be an indication of on the condenser pressure that is detected by the
dirty condenser tubes. condenser transducer.
5. Check the compressor discharge temperature on
Operating inspections the SYSTEM Screen. During normal operation
By following a regular inspection using the display discharge temperature should not exceed 220°F
readings of the OptiView™ Control Center, and main- (104°C).
tenance procedure, the operator will avoid serious op- 6. Check the compressor motor current on the SYS-
erating difficulty. The following list of inspections and TEM Screen.
procedures should be used as a guide.

Chiller Location
CENTRIFUGAL
LIQUID CHILLER LOG SHEET System No.
Date
Time
Hour Meter Reading
O.A. Temperature Dry Bulb / Wet Bulb / / / / / / / / / /
Discharge Temperature
ure
Compressor
pped)
PRV % Open (If equipped)
Input Power
% Input FLA
Motor
% Motor FLA
DC Bus Voltage
perature
Magnetic Bearing Motor Housing Temperature
Controller Rotor Elongation
L
Suction Pressure GA
IFU
Refrigerant Corresponding Temperature
perature
N TR
Small Temperature Difference 2 CE
C
Evaporator

Supply Temperature YM
Supply Pressure
Liquid

Return Temperature
Return Pressure
Flow Rate - GPM (If equipped)
Discharge Pressure
Corresponding Temperature
perature ...an Energy-Sa
Refrigerant

ving
mperature
Subcooler Liquid Temperature approach to you
r
Small Temperature Difference Service needs..
.
Condenser

Refrigerant Level
Issue Date:
Supply Temperature June 30, 2011
Form 160.78-MR1
Supply Pressure (611)
New Release
Liquid

Return Temperature
Return Pressure
Flow Rate - GPM (If equipped)
Remarks: Form 160.78-MR1 (611)
New Release
Issue Date: June 30, 2011

LD16236

* NOTE: A
 pad of 50 log sheets can be ordered from your local Johnson Controls branch by
requesting Form 160.78-MR1.

Figure 4 - Liquid chiller log sheets

14 JOHNSON CONTROLS
Form 160.78-O1
Section 2 - System operating procedures
Issue date: 05/19/2021

7. Check for any signs of dirty or fouled condenser To stop the chiller, complete the following steps:
tubes. The temperature difference between water
leaving condenser and saturated condensing tem- 1. Push the soft shutdown key on the Home screen
perature should not exceed the difference record- of the OptiViewTM panel. The compressor will
stop automatically. In the event of an unusual cir- 2
ed for a new unit by more than 4°F (2.2°C).
cumstance requiring immediate stoppage, a safety
Weekly stop switch is located on the side of the control
panel. Normal stop eases the driveline to stop and
• Check the refrigerant charge. See Checking the
should always be used instead of the safety stop
refrigerant charge during unit shutdown in Sec-
during regular operation.
tion 3 - Maintenance.
2. Stop the chilled water pump. If the pump is not
Monthly wired into the Microcomputer Control Center, it
• Leak check the entire chiller. turns off automatically. The actual water pump
contact operation depends on the selection on the
Semi-annually (or more often as required) SETUP screen.
• Check controls.
3. Open the switch to the cooling tower fan motors,
Annually (more often if necessary) if used.
1. Evaporator and Condenser. Prolonged shutdown
a. Inspect and clean water strainers. If the chiller must be shut down for an extended period
b. Inspect and clean tubes as required. of time, for example, over the winter season, complete
the following procedure:
c. Inspect end sheets.
1. Test all system joints for refrigerant leaks with a
2. Compressor Drive Motor. leak detector. If any leaks are found, they should
• Meg motor windings. be repaired before allowing the system to stand
for a long period of time.
3. Inspect and service electrical components as nec-
essary. During long idle periods, the tightness of the sys-
tem should be checked periodically.
4. Perform refrigerant analysis.
2. If freezing temperatures are encountered while
Need for maintenance or service the system is idle, carefully drain the cooling wa-
ter from the cooling tower, condenser, condenser
If the system is malfunctioning in any manner or the pump, and the chilled water system-chilled water
unit is stopped by one of the safety controls, see the pump and coils.
Operation Analysis Chart shown in Table 3 (Section 4
- Troubleshooting). After consulting this chart, if you Open the drains on the evaporator and condenser
are unable to make the correct repairs or adjustments liquid heads to ensure complete drainage. Drain
to start the compressor or the particular issue continues the VSD cooling system.
to hinder the performance of the unit, call the nearest
3. If freezing temperatures are encountered for peri-
Johnson Controls District Office. Failure to report con-
ods longer than a few days, the refrigerant should
stant troubles could damage the unit and increase the
be recovered to containers to prevent leakage
cost of repairs.
from O-ring joints.
Stopping the system 4. On the SETUP Screen, disable the clock. This
conserves the battery.
The OptiView™ Control Center can be programmed
to start and stop automatically (maximum - once each 5. Open the main disconnect switches to the com-
day) whenever required. Refer to the YMC2 OptiViewTM pressor motor, condenser water pump and the
Control Center Operation Manual (Form 160.78-O1). chilled water pump. Open the 115 V circuit to the
Control Center.

JOHNSON CONTROLS 15
 Form 160.78-O1
Issue date: 05/19/2021

THIS PAGE INTENTIONALLY LEFT BLANK

16 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Section 3 - Maintenance

Renewal parts
For any required Renewal Parts, refer to the YMC2 Unit To test with R-22, complete the following steps:
Renewal Parts Manual (Form 160.78-RP1). 3
1. With no pressure in the system, charge R-22 gas
Checking system for leaks into the system through the charging valve to a
pressure of 2 psig (14 kPa).
Leak testing during operation
2. Build up the system pressure with dry nitrogen
The refrigerant side of the system is carefully pressure to approximately 75 psig to 100 psig (517 kPa to
tested and evacuated at the factory. 690 kPa). To be sure that the concentration of re-
frigerant has reached all parts of the system test
After the system has been charged, the system should
for the presence of refrigerant with a leak detector
be carefully leak tested with a R-134a compatible leak
at an appropriate service valve.
detector to be sure all joints are tight.
3. Test around each joint and factory weld. It is im-
If any leaks are indicated, they must be repaired im-
portant that this test be thoroughly and carefully
mediately. Usually, leaks can be stopped by tighten-
done, spending as much time as necessary and us-
ing flare nuts or flange bolts. However, for any major
ing a good leak detector.
repair, the refrigerant charge must be removed. See
Handling refrigerant for dismantling and repairs in 4. To check for refrigerant leaks in the evaporator
this section. and condenser, open the vents in the evaporator
and condenser heads and test for the presence of
Conducting R-22 pressure test refrigerant. If no refrigerant is present, the tubes
and tube sheets may be considered tight. If refrig-
With the R-134a charge removed and all known leaks
erant is detected at the vents, remove the heads,
repaired, the system should be charged with a small
locate the leak using a soap test or leak detector,
amount of R-22 mixed with dry nitrogen so that a ha-
and repair the leak.
lide torch or electronic leak detector can be used to de-
tect any leaks too small to be found by the soap test.

LD00949

Figure 5 - Evacuation of chiller

JOHNSON CONTROLS 17
 Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

Table 1 - System pressures

*Gauge Absolute
Boiling
Inches of temperatures
mercury (Hg) Millimeters of
below one psia of mercury Microns water
standard (Hg) °F
atmosphere

0 in. 14.6960 760.00 760,000 212

10.240 in. 9.6290 500.00 500,000 192
22.050 in. 3.8650 200.00 200,000 151
25.980 in. 1.9350 100.00 100,000 124
27.950 in. 0.9680 50.00 50,000 101
28.940 in. 0.4810 25.00 25,000 78
29.530 in. 0.1920 10.00 10,000 52
29.670 in. 0.1220 6.30 6,300 40
Water
29.720 in. 0.0990 5.00 5,000 35
Freezes
29.842 in. 0.0390 2.00 2,000 15
29.882 in. 0.0190 1.00 1,000 1
29.901 in. 0.0100 0.50 500 -11
29.917 in. 0.0020 0.10 100 -38
29.919 in. 0.0010 0.05 50 -50
29.9206 in. 0.0002 0.01 10 -70
29.921 in. 0 0 0

*One standard atmosphere = 14.696 psia Notes: psia = lb per sq. in. gauge pressure
= 760 mm Hg absolute pressure at 32°F = Pressure above atmosphere
psia = lb per sq. in. absolute pressure
= 29.921 in. Hg absolute at 32°F
=S um of gauge plus atmospheric
pressure

Vacuum testing
Ensure power is removed from the input Figure 5 and start the pump. See Vacuum dehy-
side of the VSD at all times when the dration in this section.
chiller is under vacuum (less than atmo-
2. Open wide all system valves. Be sure all valves to
spheric pressure). The VSD maintains
the atmosphere are closed.
voltage to ground on the motor when the
chiller is off while voltage is available to 3. Operate the vacuum pump in accordance with
the VSD. Insulating properties in the mo- Vacuum dehydration in this section until a wet
tor are reduced in vacuum and may not bulb temperature of 32°F (0°C) or a pressure of 5
insulate this voltage sufficiently. mm Hg is reached. See Table 1 for corresponding
pressure values.
After the pressure test has been completed, the vacuum
test should be conducted as follows: 4. To improve evacuation circulate hot water, not
to exceed 125°F (51.7ºC) through the evapora-
1. Connect a high capacity vacuum pump, with in- tor and condenser tubes to thoroughly dehydrate
dicator, to the system charging valve as shown in

18 JOHNSON CONTROLS
Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

the shells. If a source of hot water is not readily Operation

available, use a portable water heater. Do not use A refrigerant system can be dehydrated using this
steam. method because the water present in the system reacts
Connect a hose between the source of hot water to changes in a similar way that a refrigerant does.
under pressure and the evaporator head drain con- By pulling down the pressure in the system to a point
nection, out the evaporator vent connection, into where its saturation temperature is considerably be-
low room temperature, heat will flow from the room
3
the condenser head drain, and out the condenser
vent. To avoid the possibility of causing leaks, through the walls of the system and vaporize the water,
raise the temperature slowly so that the tubes and allowing a large percentage of it to be removed by the
shell are heated evenly. vacuum pump. The length of time necessary for the de-
hydration of a system depends on the size or volume of
5. Close the system charging valve and the stop the system, the capacity and efficiency of the vacuum
valve between the vacuum indicator and the vac- pump, the room temperature and the quantity of water
uum pump. Then disconnect the vacuum pump present in the system. By the use of the vacuum indi-
leaving the vacuum indicator in place. cator as suggested, the test tube will be evacuated to
6. Hold the vacuum obtained in Step 3 above in the the same pressure as the system, and the distilled water
system for 8 hours; the slightest rise in pressure will be maintained at the same saturation temperature
indicates a leak or the presence of moisture, or as any free water in the system, and this temperature
both. If after 24 hours the wet bulb temperature can be observed on the thermometer.
in the vacuum indicator has not risen above 40°F
If the system has been pressure tested and found to be
(4.4°C) or a pressure of 6.3 mm Hg, the system
tight before evacuation, then the saturation temperature
may be considered tight.
recordings should follow a curve similar to the satura-
Be sure the vacuum indicator is valved off tion curve shown in Figure 6.
while holding the system vacuum and be The temperature of the water in the test tube will drop
sure to open the valve between the vacuum as the pressure decreases, until the boiling point is
indicator and the system when checking reached, at which point the temperature will level off
the vacuum after the 8 hour period. and remain at this level until all of the water in the
shell is vaporized. When this final vaporization has
7. If the vacuum does not hold for 8 hours within the taken place the pressure and temperature will continue
limits specified in Step 6, the leak must be found to drop until eventually a temperature of 35°F (1.6°C)
and repaired. or a pressure of 5 mm Hg is reached.

Vacuum dehydration
To obtain a sufficiently dry system, use the following
procedure to evacuate and dehydrate a system in the
field. Although there are several methods of dehydrat-
ing a system, this method produces some of the best
results and provides accurate readings as to the extent
of dehydration.
The equipment required to follow this method of de-
hydration consists of a wet bulb indicator or vacuum
gauge, a chart showing the relation between dew point
temperature and pressure in inches of mercury in a
vacuum (see Table 1), and a vacuum pump capable of LD00474

pumping a suitable vacuum on the system. Figure 6 - Saturation curve

JOHNSON CONTROLS 19
 Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

When this point is reached, practically all of the air system pressure is raised above the point correspond-
has been evacuated from the system, but there is still ing to the freezing point of the evaporator liquid. For
a small amount of moisture left. In order to provide water, the pressure corresponding to the freezing point
a medium for carrying this residual moisture to the is 29 psig (200 kPa) for R-134a (at sea level).
vacuum pump, nitrogen must be introduced into the
system to bring it to atmospheric pressure and the indi- While charging, every precaution must be taken to pre-
cator temperature will return to approximately ambient vent moisture laden air from entering the system. Make
temperature. Close off the system again, and start the up a suitable charging connection from new copper
second evacuation. tubing to fit between the system charging valve and the
fitting on the charging drum. This connection should
The relatively small amount of moisture left will be be as short as possible but long enough to permit suf-
carried out through the vacuum pump and the tem- ficient flexibility for changing drums. The charging
perature or pressure shown by the indicator should connection should be purged each time a full container
drop uniformly until it reaches a temperature of 35°F of refrigerant is connected and changing containers
(1.6°C) or a pressure of 5 mm Hg. should be done as quickly as possible to minimize the
loss of refrigerant.
When the vacuum indicator registers this tempera-
ture or pressure, it is a positive sign that the system Refrigerant is furnished in cylinders that contain ei-
is evacuated and dehydrated to the required limit. If ther 30 lb, 50 lb, 125 lb, 1,025 lb, or 1750 lb. (13.6 kg,
this level cannot be reached, it is evident that there is a 22.6 kg, 56.6 kg, 464 kg, or 794 kg) of refrigerant.
leak somewhere in the system. Any leaks must be cor-
rected before the indicator can be pulled down to 35°F Checking the refrigerant charge during
(1.6°C) or 5 mm Hg in the primary evacuation. unit shutdown
During the primary pulldown, makes sure that the wet The refrigerant charge is specified for each chiller
bulb indicator temperature does not fall below 35°F model in Table 2. Charge the correct amount of refrig-
(1.6°C). If the temperature is allowed to fall to 32°F erant and record the level in the evaporator sight glass.
(0°C), the water in the test tube will freeze, and the
The refrigerant charge should always be checked and
result will be a faulty temperature reading.
trimmed when the system is shut down.
Refrigerant charging Charge the refrigerant in accordance with the method
To avoid the possibility of freezing liquid within the shown in Refrigerant charging in this section. The
evaporator tubes when charging an evacuated system, weight of the refrigerant charged should be recorded
only refrigerant vapor from the top of the drum or cyl- after initial charging.
inder must be admitted to the system pressure until the

Table 2 - Refrigerant charge

Estimated refrigerant
Compressor Evaporator Condenser
charge, lb (kg) 1

EA2510 CA2110 570 (260)

M1-197FAA EA2510 CA2510 625 (285)

EA2514 CA2514 860 (390)

EA2510 CA2110 555 (255)

M2-205FAA EA2510 CA2510 610 (280)

EA2514 CA2514 860 (390)

1 Refrigerant charge quantity and weights will vary based on tube count.
Refer to product drawings for detailed weight information.

20 JOHNSON CONTROLS
Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

Handling refrigerant for dismantling and dition.

repairs
Cleaning evaporator and condenser tubes
If it becomes necessary to open any part of the refriger-
ant system for repairs, it will be necessary to remove Evaporator
the charge before opening any part of the unit. If the It is difficult to determine by any particular test wheth-
chiller is equipped with optional valves, the refriger- er possible lack of performance of the water evaporator 3
ant can be isolated in either the condenser or in the is due to fouled tubes alone or due to a combination
evaporator or compressor while making any necessary of troubles. Trouble which may be due to fouled tubes
repairs. is indicated when, over a period of time, the cooling
capacity decreases and the split (temperature differ-
Megging the motor ence between water leaving the evaporator and the
Electrical test of motor winding resistance should be refrigerant temperature in the evaporator) increases. A
performed by a qualified service technician because gradual drop-off in cooling capacity can also be caused
it involves determination of power leads between the by a gradual leak of refrigerant from the system or by
motor and the VSD. Results from these winding insu- a combination of fouled tubes and shortage of refriger-
lation resistance tests should be trended each interval ant charge.
to determine degradation in motor windings.
Condenser
Condensers and evaporators In a condenser, trouble due to fouled tubes is usually
indicated by a steady rise in head pressure, over a pe-
General riod of time, accompanied by a steady rise in condens-
Maintenance of condenser and evaporator shells is im- ing temperature.
portant to provide trouble free operation of the chiller.
The water side of the tubes in the shell must be kept Tube fouling
clean and free from scale. Correct maintenance proce- Fouling of the tubes can be due to the following types
dures such as tube cleaning, and testing for leaks, is of deposits:
covered on the following pages.
1. Rust or sludge – which finds its way into the tubes
Chemical water treatment and accumulates there. This material usually does
not build up on the inner tube surfaces as scale,
Since the mineral content of the water circulated
but does interfere with the heat transfer. Rust or
through evaporators and condensers varies with almost
sludge can generally be removed from the tubes
every source of supply, it is possible that the water be-
by a thorough brushing process.
ing used may corrode the tubes or deposit heat resistant
scale in them. Reliable water treatment companies are 2. Scale – due to mineral deposits. These deposits,
available in most larger cities to supply a water treat- even though very thin and scarcely detectable
ing process which will greatly reduce the corrosive and upon physical inspection, are highly resistant to
scale forming properties of almost any type of water. heat transfer. They can be removed effectively by
circulating an acid solution through the tubes.
As a preventive measure against scale and corrosion
and to prolong the life of evaporator and condenser
tubes, a chemical analysis of the water should be made
preferably before the system is installed. A reliable wa-
ter treatment company can be consulted to determine
whether water treatment is necessary, and if so, to fur-
nish the proper treatment for the particular water con-

JOHNSON CONTROLS 21
 Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

Tube cleaning procedures Testing for evaporator and condenser tube

leaks
Brush cleaning of tubes
Evaporator and condenser tube leaks in R-134a sys-
If the tube consists of dirt and sludge, it can usually
tems may result in refrigerant leaking into the water
be removed by means of the brushing process. Drain
circuit, or water leaking into the shell depending on the
the water sides of the circuit to be cleaned using cool-
pressure levels. If refrigerant is leaking into the water,
ing water or chilled water, remove the heads, and thor-
it can be detected at the liquid head vents after a period
oughly clean each tube with a soft bristle bronze or
of shutdown. If water is leaking into the refrigerant,
nylon brush. Do not use a steel bristle brush. A steel
system capacity and efficiency will drop off sharply. If
brush may damage the tubes.
a tube is leaking and water has entered the system, the
Improved results can be obtained by admitting water evaporator and condenser should be valved off from
into the tube during the cleaning process. This can be the rest of the water circuit and drained immediately to
done by mounting the brush on a suitable length of prevent severe rusting and corrosion. The refrigerant
1/8 in. pipe with a few small holes at the brush end system should then be drained and purged with dry ni-
and connecting the other end by means of a hose to the trogen to prevent severe rusting and corrosion. If a tube
water supply. leak is indicated, use the following steps to determine
the exact location of the leak:
The tubes should always be brush cleaned before acid
cleaning. 1. Remove the heads and listen at each section of
tubes for a hissing sound that would indicate gas
Acid cleaning of tubes leakage. This helps you to locate the section of
If the tubes are fouled with a hard scale deposit, they tubes that must be further investigated. If the
may require acid cleaning. Before acid cleaning, it is probable location of the leaky tubes has been de-
important to clean the tubes using the brushing pro- termined, treat that section in the following man-
cess described in Brush cleaning of tubes. If the rela- ner. If the location is not definite, all the tubes
tively loose foreign material is removed before the acid must be investigated.
cleaning, the acid solution will have less material to 2. Wash off both tube heads and the ends of all tubes
dissolve and flush from the tubes with the result that with water.
a more satisfactory cleaning job will be accomplished
Do not use carbon tetrachloride for this
with a probable saving of time.
purpose because its fumes give the same
Acid cleaning should only be performed flame discoloration that the refrigerant
by an expert. Consult your local water does.
treatment representative for assistance
in removing scale buildup and preventa-
tive maintenance programs to eliminate 3. With nitrogen or dry air, blow out the tubes to
future problems. clear them of traces of refrigerant laden moisture
Commercial acid cleaning from the circulation water. As soon as the tubes
are clear, firmly insert a cork into each end of the
In many major cities, commercial organizations now tube. Pressurize the dry system with 50 psig to
offer a specialized service of acid cleaning evaporators 100 psig (345 kPa to 690 kPa) of nitrogen. Repeat
and condensers. If acid cleaning is required, use this this with all of the other tubes in the suspected
type of organization. The Dow Industries Service Divi- section or, if necessary, with all the tubes in the
sion of the Dow Chemical Company, Tulsa, Oklahoma, evaporator or condenser. Allow the evaporator or
with branches in principal cities is one of the most reli- condenser to remain corked up to 12 to 24 hours
able of these companies. before proceeding. Depending upon the amount

22 JOHNSON CONTROLS
Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

of leakage, the corks may blow from the end of a 6. If any of the tube sheet joints are leaking, the leak
tube, indicating the location of the leakage. If not, should be indicated by the detector. If a tube sheet
if will be necessary to make a very thorough test leak is suspected, its exact location may be found
with the leak detector. by using a soap solution. A continuous buildup of
bubbles around a tube indicates a tube sheet leak.
4. After the tubes have been corked for 12 to 24
hours, have two people carefully test each tube at Compressor 3
both ends of the evaporator. One person can re-
move corks at one end of the evaporator and the Maintenance for the compressor assembly consists of
second person can remove corks at the opposite observing the operation of the compressor.
end and handle the leak detector. Start with the top If the control panel warns of excessive landings of the
row of tubes in the section being investigated. Re- magnetic bearing motor, notify the nearest Johnson
move the corks at the ends of one tube simultane- Controls office to request the presence of a Johnson
ously and insert the exploring tube for 5 seconds. controls Service Technician. The technician can assess
This should be long enough to draw into the de- the condition of the touchdown bearings using elec-
tector any refrigerant gas that might have leaked tronic tools.
through the tube walls. Place a fan at the end of
the evaporator opposite the detector. This ensures Electrical controls
that any leakage wi travel through the tube to the
detector. For information covering the OptiView™ Control
Center operation, refer to the YMC2 OptiViewTM Con-
5. Mark any leaking tubes for later identification. trol Center Operations Manual (Form 160.78-O2).

JOHNSON CONTROLS 23
 Form 160.78-O1
Section 3 - Maintenance
Issue date: 05/19/2021

Maintenance inspections for YORK YMC2 Monthly (or more often as required)
chillers • Log and compare the VSD input voltage current
To avoid serious operating difficulty, follow a regular for balanced values in the readings.
inspection procedure. Use the following list of inspec- • Verify that the unit setpoints have not been
tions and procedures as a guide. changed. Check the setpoints in the Security Log
screen.
Daily
• Check the OptiView™ Control Center display. • Verify that the evaporator and condenser water
Log the date, time, run hours, and number of flows are within rated limits.
starts. • Check the operation of the motor starter. Monitor
• Use the daily log in the YMC centrifugal liquid
2 at unit start-up for any abnormalities.
chiller log sheet, Form 160.78-MR1, to log all of Annually (more often if necessary)
the unit operating data that is outlined in the log.
Use this data for the following comparisons: • For the evaporator and condenser, complete the
following inspections:
• Compare the entering and leaving condenser
water temperatures with the job design con- • Inspect and clean the water strainers.
ditions. Check the condenser water tempera- • Inspect and clean the tubes as required.
tures on the System screen.
• Inspect the end sheet.
• Compare the entering and leaving chilled
liquid temperatures and evaporator pressure • For the compressor drive motor, measure the mo-
with the job design conditions. Check the tor winding insulation resistance (megohm test-
chilled liquid temperatures on the System ing).
screen. • Check and tighten all of the electrical components
• Check the condenser saturation temperature as necessary
on the System screen. The condenser satu- • Clean and backflush the VSD heat exchanger.
ration temperature is based on the condens-
er pressure that is sensed by the condenser • Replace the VSD coolant.
transducer. • Perform refrigerant analysis.
• Check the compressor discharge temperature • For all HYP model VSDs, conduct a Smart Sensor
on the System screen. During normal opera- annual test.
tion, the discharge temperature does not ex-
ceed 220°F (104°C). • Review the operating data for trends that indicate
increasing vibration or power consumption.
• Check the compressor motor current on the
Compressor screen.

Weekly
• Check the refrigerant charge. See Checking the
refrigerant charge during unit shutdown.
• Check for any signs of dirty or fouled condenser
tubes. The temperature difference between the
water leaving the condenser and the saturated
condensing temperature must not exceed the dif-
ference recorded for a new unit by more than 4°F
(2.2°C).

24 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

Section 4 - Troubleshooting

Table 3 - Operation analysis chart

Results Possible cause Remedy

4
1. Symptom: abnormally high discharge pressure

Temperature difference between

Condenser tubes dirty
condensing temperature and water off Clean condenser tubes. Check water conditioning.
or scaled.
condenser higher than normal.

Condenser tubes dirty

Clean condenser tubes. Check water conditioning.
or scaled.
High discharge pressure.
High condenser water Reduce condenser water inlet temperature. Check
temperature. cooling tower and water circulation.

Temperature difference between condenser

Insufficient Increase the quantity of water through the
water on and water off higher than normal,
condensing water flow. condenser to the correct value.
with normal evaporator pressure.

2. Symptom: abnormally low suction pressure

Insufficient charge of
Temperature difference between leaving Check for leaks and charge refrigerant into system.
refrigerant.
chilled water and refrigerant in the
evaporator greater than normal with normal
Variable orifice
discharge temperature. Remove obstruction.
problem.

Temperature difference between leaving

chilled water and refrigerant in the Evaporator tubes dirty
Clean evaporator tubes.
evaporator greater than normal with normal or restricted.
discharge temperature.

Temperature of chilled water too low with Insufficient load for Check capacity control operation and setting of low
low motor amperes. system capacity. water temperature shutdown setpoint.

3. Symptom: high evaporator pressure

Capacity control failed Check the PRV (if applicable), VGD, and hot gas
to load. bypass (if applicable) positioning circuits.

High chilled water temperature.

Be sure the capacity control devices and speed
System overload. increased (without overloading the motor) until the
load decreases.

JOHNSON CONTROLS 25
 Form 160.78-O1
Issue date: 05/19/2021

THIS PAGE INTENTIONALLY LEFT BLANK

26 JOHNSON CONTROLS
Form 160.78-O1
Issue date: 05/19/2021

The following factors can be used to convert from

English to the most common SI metric values.

Table 4 - SI metric conversion

Measurement Multiply English unit By factor To obtain metric unit

Capacity Tons refrigerant effect (ton) 3.516 Kilowatts (kW)

Power Horsepower 0.7457 Kilowatts (kW)

Flow rate Gallons / minute (gpm) 0.0631 Liters / second (L/s)

Feet (ft) 0.3048 Meters (m)

Length
Inches (in.) 25.4 Millimeters (mm)

Weight Pounds (lb) 0.4538 Kilograms (kg)

Velocity Feet / second (fps) 0.3048 Meters / second (m/s)

Feet of water (ft) 2.989 Kilopascals (kPa)

Pressure drop
Pounds / square inch (psi) 6.895 Kilopascals (kPa)

Temperature
To convert degrees Fahrenheit (°F) to degrees Celsius
(°C), subtract 32° and multiply by 5/9 or 0.5556.
Example: (45.0°F - 32°) x 0.5556 = 27.2°C
To convert a temperature range (i.e., a range of 10°F)
from Fahrenheit to Celsius, multiply by 5/9 or 0.5556.
Example: 10.0°F range x 0.5556 = 5.6 °C range

JOHNSON CONTROLS 27
5000 Renaissance Drive, New Freedom, Pennsylvania USA 17349 1-800-524-1330 Subject to change without notice. Printed in USA
Copyright © by Johnson Controls 2021 www.johnsoncontrols.com ALL RIGHTS RESERVED
Form 160.78-O1 (521)
Issue Date: May 19, 2021
Supersedes: 160.78-O1 (820)