Carrier 38MGR Series Service Manual page 41

DIAGNOSIS AND SOLUTION (CONT)
Communication malfunction between IPM board and outdoor main board) error diagnosis (E3)
ERROR CODE
MALFUNCTION DECISION
CONDITIONS
SUPPOSED CAUSES
Troubleshooting
38MGR-04SM
E3
PCB main chip does not receive feedback from IPM module during 60 seconds.
• Wiring mistake
• PCB faulty
Communication malfunction between
IPM board and outdoor main board.
Is there at least one LED in
the IPM board that is illuminated?
No
Check the signal wire between
the IPM module and the main
board. Is it connected well?
No
Reconnect and retry.
Does the error still appear?
No
Replace the IPM board, and
check if the system runs normally.
No
Replace the outdoor main
board, and then check if the
system can run normally.
No
Replace the electric
control box.
Specifications subject to change without notice.
Yes
Yes
No
Yes
Yes
Problem solved.
41