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Troubleshooting
No
Cooling
24v between
between R
No
Y & C at
& C at
thermostat?
thermostat?
Yes
24v at DFC
24v to
No
reversing vave
terminals O-RV
& C-RV?
coil?
Yes
Are both
compressor and
No
Is there 24v
condenser fan
at contactor
motor running?
Yes
208/240v
Is indoor
No
between C & G
blower motor
at thermostat?
running?
Yes
Is indoor
No
blower motor
speed correct?
Yes
Is unit
No
producing
cool air?
Yes
24v
24 volts at
No
No
transfomer
secondary?
Yes
Yes
No
24v at DFC
No
terminals C &
O?
Yes
Yes
24v at
No
No
terminals
CNT & C on
coil?
DFC?
Yes
Yes
Is compressor or
No
condenser fan running
independently?
Yes
Compressor
No
208/240v
Yes
No
between L & N
at motor
harness?
Yes
T1/2/3/4/5 terminals
208/240v at
208/240v at
No
L1 & L2 to
transformer
contactor?
primary?
Yes
Yes
Is contactor
No
plunger pulled
in?
Yes
0vac across L1
& T1 terminals
of contactor?
Yes
No
running?
Yes
Condenser
0v at DF1 &
fan motor
DF2 terminals
not running
on DFC?
Check for 24v
No
between C &
at motor
Yes
Heat Pump - Cooling (1 Stage)
No
Check disconnect circuit
breaker fuses
Check wiring between contactor
and transformer
Replace transformer
Check low voltage fuse
thermostat or wiring
Check thermostat or wiring
Check thermostat & wiring
Replace PCB
Repalce reversing valve coil
Check open safety or faulty
wiring
Check contactor coil
Check wiring or replace
contactor
No
Replace contactor
Check capacitor wiring
Check open compressor
overload faulty compressor
capacitor or wiring
No
Replace PCB
Yes
Check capacitor condenser fan
motor or wiring
Check thermostat or wiring
Check line voltage wiring to
blower motor
Check low voltage wiring to
motor or motor controller
Check blower motor
See "airflow adjustments"
section
Check faulty reversing valve or
faulty compressor
45
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