Carrier 40MFC - Inverter Compressor Drive Error Diagnosis and Solution (P4)

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9 --- Inverter compressor drive error --- diagnosis and solution (P4)
Error Code P4
Malfunction conditions
An abnormal inverter compressor drive is detected by a special detection circuit. This includes
communication signal, voltage, and compressor rotation speed signal detections to mention
some.
Possible Causes
• Wiring mistake
• IPM malfunction
• Defective outdoor fan assembly
• Defective compressor malfunction
• Defective PCB
Trouble shooting:
Check if the wiring between main
PCB and compressor is connected
incorrectly and if the wires and
connectors are broken?
Correct the connection or replace
the wires and connectors.
Yes
No
IPM continuity check. Check if the
IPM terminal resistance values are
uniform.
Replace the IPM board or replace the
main PCB if the IPM board and main
PCB are integrated together.
No
Check if the outdoor fan runs
properly or the outdoor unit
ventilation is good.
Yes
No
Refer to the Notes below, check whether the
resistance of the fan motor is normal. If not, replace
the fan motor.
Yes
Check if the compressor resistance
values are uniform .
No Replace the compressor.
Yes
Replace the outdoor main PCB if the
main PCB and IPM are separate.
A14489
Note:
Measure the black p in and red pin of the motor terminals, the resistance should be around the value specified below:
Model size
Voltage
Resistance Value at
68_F(20_FC)
9K and 12K 115 50Ω
12K
208-230
293Ω
18K AC / 17K HP 84.5Ω
22K 88.5Ω