P4 Flow Chart - Lennox MPA012S4S-1L Service Manual

Compressor Drive Error
Check wiring connections between compressor and
main PCB.
Check the IPM
Check the outdoor fan and the outdoor unit ventilation.
Check the compressor resistance values.
Replace the outdoor main PCB.

P4 Flow Chart

Yes
No
No
Yes
No
Yes
No
Yes
Make necessary corrections.
Replace the IPM board or replace the
main PCB.
Refer to the fault code fan speed malfunc-
tion (E8).
Replace the compressor.
Lennox Mini-Split Service Manual / Page 233