SERVICING
17
Checking Voltage
WARNING
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be present.
Failure to do so may cause property damage,
personal injury or death.
1. Remove doors, control panel cover, etc. from unit
being tested.
With power ON:
WARNING
Line voltage now present
2. Using a voltmeter, measure the voltage across
terminals L1 and L2 of the contactor.
3. No reading - indicates open wiring, open fuse(s) no
power or etc. from unit to fused disconnect service.
Repair as needed.
4. If incoming voltage is within the range listed in the
chart below, energize the unit.
5. Using a voltmeter, measure the voltage with the unit
starting and operating to determine if voltage is within
the range listed in the chart below.
6. If the voltage falls below the minimum voltage, check
the line wire size. Long runs of undersized wire can
cause low voltage. If the wire size is adequate, notify
the local power company regarding either low or high
voltage.
Unit Voltage
Rated Voltage
Min. Supply
Voltage
Max. Supply
Voltage
208/230V
197
253
Checking Wiring
WARNING
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be present.
Failure to do so may cause property damage,
personal injury or death.
1. Check wiring visually for signs of overheating,
damaged insulation and loose connections.
2. Use an ohmmeter to check continuity of any
suspected open wires.
3. If any wires must be replaced, replace with
comparable gauge and insulation thickness.
Branch Circuit Am
-
pacity
15 20 25 30 35 40 45 50
SUPPLY WIRE
LENGTH - FEET
200
6
4
4
4
3
3
2
2
150
8
6
6
4
4
4
3
3
100
10 8
8
6
6
6
4
4
50
14 12 10 10 8
8
6
6
Wiring Table
Checking Thermostat and Wiring
Thermostat Wiring: The maximum wire length for 18 AWG
thermostat wire is 100 feet.
A/GPDM3
Terminal
24-48
Thermostat
Red
R (24V)
Green
G (fan)
Orange
O (Rev. Value)
White
W1 (Heat, 2nd)
Brown
W2 (Heat, 3rd)
Yellow
Y (Cool)
Blue
C (24V Common)
WARNING
Line voltage now present
With power ON, thermostat calling for cooling
1. Use a voltmeter to check for 24 volts at thermostat
wires C and Y in the condensing unit control panel.
2. No voltage indicates trouble in the thermostat, wiring
or external transformer source.
3. Check the continuity of the thermostat and wiring.
Repair or replace as necessary.
Indoor Blower Motor
With power ON:
WARNING
Line voltage now present
1. Set fan selector switch at thermostat to “ON”
position.
2. With voltmeter, check for 24 volts at wires C and G.
3. No voltage indicates the trouble is in the thermostat
or wiring.
4. Check the continuity of the thermostat and wiring.
Repair or replace as necessary.
