Carrier QHC Series Service Manual page 40

10.2.2 Indoor / outdoor unit's communication diagnosis and solution(E1)
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
Replace the reactor
Replace the reactor
E1
Indoor unit does not receive the feedback from outdoor unit during
110 seconds and this condition happens four times continuously.
Wiring mistake
●
Indoor or outdoor PCB faulty
●
Power off, then restart the unit 2 minutes later
Power off, then restart the unit 2 minutes later
Yes
Measure Vs. Is the voltage moving
Measure Vs. Is the voltage moving
alternately as positive values and
alternately as positive values and
negative values?
negative values?
(Vs is the voltage between S and N of
(Vs is the voltage between S and N of
outdoor unit. Red pan-S, Black pan-N)
outdoor unit. Red pan-S, Black pan-N)
If the voltage has always been the positive value
Check the outdoor wiring connection
Check the outdoor wiring connection
Yes
Check whether reactor
Check whether reactor
No
is normal?
is normal?
Yes
Replace the outdoor main PCB.
Replace the outdoor main PCB.
Power on. Is the error
Power on. Is the error
extinguished?
extinguished?
No
Replace the indoor main PCB.
Replace the indoor main PCB.
38
If the voltage is a fixed value
Check the indoor wiring connection
Check the indoor wiring connection
Yes
Replace the indoor main PCB.
Replace the indoor main PCB.
Power on. Is the error
Power on. Is the error
extinguished?
extinguished?
No
Replace the outdoor main PCB.
Replace the outdoor main PCB.