Troubleshooting
No compressor Or fan
operation
X X
Power LED ON
Bad thermostat
connection / faulty
thermostat
Check thermostat and wiring. Check unit terminal
block for 24 VAC between "Y" and "C" and "G" and
"C."
Power LED OFF
Low or no supply
power
Ensure that the supply voltage to the unit is with in
the range shown on the unit data plate.
Faulty control
transformer
Check for 24 VAC between "R" and "C" on the unit
terminal block. For 75 and 100 VA transformers,
check that the transformer circuit breaker has not
tripped. Check low voltage circuit for overload
conditions or short circuits before replacing the
transformer.
No Fan operation—
constant Airflow
motor
X X See Action
No fan operation
signal
• Make sure all CFM DIP switches are in the
proper configuration (refer to the blower
performance tables).
• Check for 24V between R & C on ECM
board.
• M
ove FAN switch to ON at thermostat.
Check fo
r 24V at G & C (should be the
same as R & C) terminals on ECM board. If
no voltage is present from G to C, examine
the thermostat or thermostat wires.
• Check high voltage at the ECM motor
harness
circuit. If no voltage is present,
ensure that high voltage is present to the
unit. For 208/230V at L1 & L2 (black and
white wire), for 265/277V at L1 & N (must
be within 10%).
• Check the 16-pin harness connection and
continui
ty for each wire. If any pin does not
have continuity, change the harness.
• On the ECM Interface board, set the DIP
switch to T
est (ON) while verifying that G
to C has 24 volts. If the motor does not
start, replace the ECM motor. If the motor
starts, replace the ECM Interface Board.
Loose wiring
Interface board
problem
Faulty motor
Unit Troubleshooting
Problem
Mode
Check Possible Cause Action
Cooling Heating
| 55
RF Series Heat Pumps — 8733980022 (2024/12)
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