Carrier 38MGRBQ18B-3 - DIAGNOSIS AND SOLUTION (CONT); Communication Malfunction Between IPM Board and Outdoor Main Control Board

38MGRBQ: Service Manual
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DIAGNOSIS AND SOLUTION (CONT)
E3/ PC 40 (Communication malfunction between IPM board and outdoor main control board) diagnosis
Troubleshooting
ERROR CODE
E3/ PC 40
MALFUNCTION DECISION
CONDITIONS
PCB main chip does not receive feedback from IPM module during 60 seconds.
SUPPOSED CAUSES
Wiring mistake
PCB faulty
Communication malfunction between
IPM board and outdoor main board
Is there at least one LED in
the IPM board light?
Check the signal wire between
the IPM module and the main
board. Is the connection good?
Reconnect and retry.
Does the error still appear?
Replace IPM board, and
then check whether the
system can run normally
Replace the electric control
box
No
No
No
No
Yes
Problem solved
No
Yes
Replace the outdoor main
board and then check the
whether the system
can run normally.
No
Yes
Yes