Carrier 40QSM009DS Service Manual page 109

16.3.10 Inverter compressor drive error diagnosis and solution(P4)
Error Code
Malfunction conditions
Potential causes
Trouble shooting:
Check the wiring between the main
PCB and compressor. Is it improperly
wired?
No
Check the IPM. Is it functioning
properly?
Yes
Check the outdoor fan and the
outdoor unit ventilation. Is it
functioning properly?
Yes
Check the compressor resistance
values. Are they within acceptable
parameters?
Yes
Replace the outdoor main PCB
P4
Abnormalities in the inverter compressor drive is detected by a
special detection circuit, which can perform communication
signal detection, voltage detection, and compressor rotation
speed signal detection.
Wiring mistake
●
IPM malfunction
●
Faulty outdoor fan assembly
●
Compressor malfunction
●
Faulty outdoor PCB
●
Yes
No
No
No
Ensure proper connection or
replace the wires and connectors
Replace the IPM board or replace
the main PCB
Please refer to "Fan Speed
Malfunction"
Replace the compressor
106