Window Type Air Conditioners

Learning Outcomes

Upon Completion of this Chapter, the students should be able

to:

1- Classify domestic air-conditioning systems.

2- Explain window type air-conditioning, including the construction
classification, principle of operation, wiring diagram and controls.
3- Outline single and multi-split systems.
4- Explain condensing unit and main construction piping insulation.
5- State the advantages and disadvantages of single and
multi-split systems.

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 Window Type Air Conditioners

1.1 Introduction

In order to obtain an air-conditioned environment in a confined

space, various types of systems and equipment are used.

The most common equipment around us are room air-conditioner

and split type air conditioner. Both of them are employed for comfort,
health and efficiency of human being. These are being produced by
various manufacturers in different shapes, sizes, features and
capacities; however, their basic construction and principle of
operation are identical. This chapter aims at explaining in details,
about window and split type air-conditioners in order to enable you
to understand their construction and principle of operation.

1.2 Classification of domestic air conditioning systems

(A) According to installation type, as shown in the table below.

1. Window type

single split unit

2. Split unit
(Single Split and Multi- split)
Multi-split unit

(B) According to function, as shown in:

1. Cooling
2. Cooling + Heating

1.3 Window type air-conditioner

4.3.1 General description

The window-type A/C is a one-piece machine, with the outdoor and
indoor parts in one case. Application is limited to room A/Cs given its
small capacity (2-2.5 TON).

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 Window Type Air Conditioners

The condenser is located in the section of the cabinet outside the

building, and the outside air is forced over the condenser by a
condenser fan. Inside the room, another fan called (blower) draws
air in, through filter and evaporator, and forces it out through the
cooled air outlet. see Figure (4.1)

Figure (4-1) Elements of a window air-conditioner

The two fans - condenser and blower - are driven through a

common multi- speed motor called fan motor.
Advantages
 Initial cost is very low.
 Quick and easy installation.
Disadvantages
 High noise
 Small capacity range
 Large temperature fluctuations
 Air delivery narrow relative to other A/C types
 Aesthetically unpleasant

1.3.2 Classifications of window type air-conditioners

Window type air-conditioner can be classified into:

1- Cooling type.
This type of air-conditioner cools the air only through its
refrigeration unit. as shown in Figure (4.2).

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 Window Type Air Conditioners

Figure (4.2) window unit (cooling type)

2- Cooling / heating type.

This type of window air-conditioner can cool the air and heat the
air by using:
 Electrical heater. See Figure (4.3).
 Reverse cycle. See Figure (4.4).

Figure (4.3) Window unit with electrical heater

Summer cooling cycle winter heating cycle

Figure (4.4) Window unit with reverse cycle

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 Window Type Air Conditioners

1.3.3 Principle of operation (cooling only)

The vapour compression refrigeration cycle, shown in Figure (4.5),

explains the operating principle of a domestic air-conditioner as
follows:

1- The compressor Pumps the refrigerant through the circuit of

tubing between the evaporator and the condenser.
2- The condenser releases the heat absorbed in the evaporator
and the heat of compression works outdoor to liquefy the
refrigerant vapour.
3- The expansion device (capillary tube) reduces the pressure
between the high and the low pressure sides of the cycle.
4- The liquid refrigerant evaporates inside the evaporator tubes
by absorbing heat from the hot air passing through the
evaporator and cools the air to the desired temperature. If this
temperature is below the dew point, water vapour in the air
starts to condense and consequently the air is dehumidified.

Figure (4.5) Refrigeration cycle of air-conditioner

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 Window Type Air Conditioners

1.3.4 Construction of window type air-conditioner

A window air conditioner consists of a blower, fan, compressor,

evaporator coil, condenser coil, thermostat and filter. as shown in
Figure (4.6)

Figure (4.6) Construction of window type A/C

1.3.4.1 Main mechanical components:

Compressor:
It pumps the refrigerant through the circuit of tubing. Figure (4.7)
shows construction of reciprocating and rotary compressors.

Figure (4-7) Cross-section of two types of compressors

(2) Evaporator and Condenser

The evaporator and condenser coils are serpentine tubing

surrounded by aluminum fins.
This tubing is usually made of copper, as shown in Figure (4.8).

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 Window Type Air Conditioners

Evaporator Condenser
Figure (4.8) Evaporator and condenser

(3) Expansion device

There are two types of expansion device are used with window type
air conditioner, as shown in Figure (4.9).
- The capillary tube.
- Automatic expansion valve (AEV)

Window A/C uses AEV Window A/C uses Capillary tube

Figure (4.9) Types of expansion device

(4) Air filter
Air filters are used with room air-conditioner in order to:
 Remove dirt from the air (purifying), to provide clean air to the
room.
 Keep dirt off the cooling coil, as shown in Figure (4.10).

Figure (4.10) Air filter

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 Window Type Air Conditioners

1.3.4.2 Main electrical components

a) Compressor motor

A single phase motor (220-240 V / 50 Hz) is used to drive the

hermetic compressor, as shown in Figure (4-11). Usually two types
of motors are used in a domestic air-conditioner:

a) Permanent capacitor motor.

a) Capacitor start capacitor runs motor.

Figure (4-11) Compressor with motor (sealed in compressor shell)

b) Fan - motor

A permanent capacitor single phase (220-240 V / 50 Hz), multi-

speed (two or three) motor is used, as shown in Figure (4-12).

Figure (4.12) fan motor

c) Louver-motor
A single phase shaded pole motor which is used to oscillate the
supplied air to the conditioned space, as shown in Figure (4.13)

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 Window Type Air Conditioners

Figure (4.13) Louver motor

d) Capacitors

There are two types of capacitor that can be used with motors of
window type air-conditioner, as shown in Figure (4.14). (Running,
starting and dual capacitor).

(a) Running capacitor

1. A (3 to 5 μF) capacitor is used with a fan-motor.
2. A (35 to 45 μF) run capacitor is used with compressor-motor.
3. A( 5, 40 μF) dual run capacitor is used for a fan and
compressor motor.

Fan capacitor compressor cap Dual capacitor (fan, comp)

Figure (4.14) run capacitors
(b) Starting capacitor
A (108 μF) or more is used with a capacitor start capacitor run motor
only, as shown in Figure (4.15).

Figure (4.15) start capacitor

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 Window Type Air Conditioners

e) Over load protector

It protects the compressor-motor against each of the following
- High current
- Over-heating.
Compressor-motor are provided with an overload protect either
external or internal mounted. As shown in figure (4.16 a,b)

Figure (4.16 a) external overload

Figure (4.16 b) internal overload and its location inside the compressor

f) Selector switch
Selector switch is used to select the desired operating conditions of
window type air-conditioner. The desired conditions may be off/low-
fan/high-fan/low- cool/high-cool, as shown in Figure(4.17).

Figure (4.17) selector switch and Thermostat of a window type A/C

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 Window Type Air Conditioners

g) Thermostat
The thermostat automatically starts and stops the running of the
compressor in the air-conditioner in order to control and maintain a
comfortable room temperature. When the room temperature reaches
the desired setting, cooling will automatically stop.
Its sensitive bulb is usually mounted at the inlet of the evaporator air
flow. See Figure (4.18)

Figure (4.18) thermostat

1.3.5 Wiring diagram

There are two main wiring diagrams for a window type conditioner
according to speed fan motor.

A. Wiring diagram of window air-conditioner using a two-speed

fan motor.
Figure (4.19a, b) shows the wiring diagram of a window type air-
conditioner using a two-speed fan motor.

Figure (4-19a) Wiring diagram of window type air-conditioner using

permanent capacitor motor

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 Window Type Air Conditioners

Figure (4.19b) Wiring diagram of window air-conditioner using

permanent capacitor motor (two-speed fan motor)

B. Wiring diagram of window air conditioner using three speed

fan motor.

Figure (4.20) shows the wiring diagram of a window type air-

conditioner using a three-speed fan motor.

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 Window Type Air Conditioners

Figure (4.20) Wiring diagram of window air-conditioner (three speed

fan motor)

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