Carrier DHMSHAQ09XA1 Service Manual page 32

DIAGNOSIS AND SOLUTION (CONT)
Inverter compressor drive error diagnosis and solution (P4)
Error Code
Malfunction decision conditions
Supposed causes
Troubleshooting
Check the wiring between main PCB
and compressor
Check the IPM
Check the outdoor fan and the
outdoor unit ventilation
Check the compressor resistance
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, etc..
·Wiring mistake
·IPM malfunction
·Outdoor fan assembly faulty
·Compressor malfunction
·Outdoor PCB faulty
No
Yes
Yes
values
Yes
Correct the connection or replace
Yes
the wires and connectors.
Replace the IPM board or replace
No
the main PCB
Please refer to the solution of
No
Speed Has Been Out Of Control
malfunction
No Replace the compressor.
32
Fan