Chapter 9 Electrical Wiring Diagram Basics 211
Copyright Goodheart-Willcox Co., Inc.
9.3 Basic Window Air-Conditioning Unit Wiring
Diagrams
The window-type unit is a plug-in appliance mounted in the window.
This unit is similar in electrical wiring confi guration to through-the-wall
units, but does not have solid sides and is not installed through the wall.
Window units are considered more of a temporary installation, while
through-the-wall unit installations require structural modifi cations. The
following factors make electrical diagrams for window and through-the-
wall units easier to understand:
■ There is typically only one fan motor on window and through-the-
wall units. The fan motor has two shafts—one to turn the condenser
fan blade and one to turn the evaporator blower.
■ The thermostat and other associated controls are all line voltage
devices. There is no control transformer.
■ No fi eld-installed wiring is required.
■ The unit has few control devices. This makes the circuits relatively
easy to trace out and evaluate.
The wiring diagram for a typical window unit is shown in Figure 9-13.
A legend is provided, denoting the electrical connections made in each mode
of system operation. Thus, these diagrams are easy to follow even though
the internal workings of the switch are not shown. For example, if the selec-
tor switch is set to the HIGH FAN position, contacts L1-1 will close on the
switch. This action causes the fan to operate at high speed, as indicated by
the current path highlighted in Figure 9-14A. If the selector switch is set to
the HIGH COOL position, contacts L1-1-C will close on the switch, which
causes the high-speed fan and the compressor to operate, Figure 9-14B.
L1
1
2
3
C
Thermostat
Run capacitor
Run capacitor
Compressor
C
S
R
Fan motor
HIGH
MEDIUM
LOW
L1 N
Selector
switch
Switch positions
Off None
Low fan L1-3
Medium fan
High fan
Low cool
Medium cool
High cool
Common
L1-2
L1-1
L1-C-3
L1-C-2
L1-C-1 Overload
Goodheart-Willcox Publisher
Figure 9-13. The schematic wiring diagram of a typical window or through-the-wall air-
conditioning unit.
Copyright Goodheart-Willcox Co., Inc.
9.3 Basic Window Air-Conditioning Unit Wiring
Diagrams
The window-type unit is a plug-in appliance mounted in the window.
This unit is similar in electrical wiring confi guration to through-the-wall
units, but does not have solid sides and is not installed through the wall.
Window units are considered more of a temporary installation, while
through-the-wall unit installations require structural modifi cations. The
following factors make electrical diagrams for window and through-the-
wall units easier to understand:
■ There is typically only one fan motor on window and through-the-
wall units. The fan motor has two shafts—one to turn the condenser
fan blade and one to turn the evaporator blower.
■ The thermostat and other associated controls are all line voltage
devices. There is no control transformer.
■ No fi eld-installed wiring is required.
■ The unit has few control devices. This makes the circuits relatively
easy to trace out and evaluate.
The wiring diagram for a typical window unit is shown in Figure 9-13.
A legend is provided, denoting the electrical connections made in each mode
of system operation. Thus, these diagrams are easy to follow even though
the internal workings of the switch are not shown. For example, if the selec-
tor switch is set to the HIGH FAN position, contacts L1-1 will close on the
switch. This action causes the fan to operate at high speed, as indicated by
the current path highlighted in Figure 9-14A. If the selector switch is set to
the HIGH COOL position, contacts L1-1-C will close on the switch, which
causes the high-speed fan and the compressor to operate, Figure 9-14B.
L1
1
2
3
C
Thermostat
Run capacitor
Run capacitor
Compressor
C
S
R
Fan motor
HIGH
MEDIUM
LOW
L1 N
Selector
switch
Switch positions
Off None
Low fan L1-3
Medium fan
High fan
Low cool
Medium cool
High cool
Common
L1-2
L1-1
L1-C-3
L1-C-2
L1-C-1 Overload
Goodheart-Willcox Publisher
Figure 9-13. The schematic wiring diagram of a typical window or through-the-wall air-
conditioning unit.