38MBR: Service Manual
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39
J4 Malfunction
Troubleshooting
Error Code J4
Malfunction decision conditions
When the signal from the IPM to the Main Control Board and IPM Board is abnormal, the display LED shows
“J4” and the unit turns off.
Supposed Causes
• Faulty wiring
• Faulty IPM Outdoor board
•Faulty Main Outdoor board
• Faulty rectifier
J4 displayed
CommunicaƟon error
between the outdoor
main chip and the
compressor drive board.
Is there at least one LED
in the compressor
drive board light?
Check the signal wire
between the
compressor drive board
and the main board, it is
connected properly?
No
Yes
Replace the
compressor drive board..
Is the system running
normally?
No
Yes
Problem solved.
Reconnect and retry.
Does the error
sƟůů exist?
No
Replace the outdoor
main board.
Is the system running
normally?
No
Replace the electric
control box.
Yes
No
Yes
Yes
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