Fisher FSAI-SU-91AE2 Service Manual page 50

8.2.10 Inverter compressor drive error diagnosis and solution (P4)
Error Code
Malfunction decision
conditions
Supposed causes
Trouble shooting:
Check the wiring between main PCB
and compressor
No
Check the IPM
Yes
Check the outdoor fan and the
outdoor unit ventilation
Yes
Check the compressor resistance
values
Yes
Replace the outdoor main PCB
P4
An abnormal inverter compressor drive is detected by a special
detection circuit, including communication signal detection,
voltage detection, compressor rotation speed signal detection
and so on.
Wiring mistake
●
IPM malfunction
●
Outdoor fan ass'y faulty
●
Compressor malfunction
●
Outdoor PCB faulty
●
Yes
No
No
No
Correct the connection or replace
the wires and connectors.
Replace the IPM board or replace
the main PCB
Please refer to the solution of 【Fan
Speed Has Been Out Of Control】
malfunction
Replace the compressor.
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