off.
P6
Check whether the voltage range 
of P-N on IPM module is normal? 
277-356VDC for 18-30KBtu/h; 277-
410VDC for 36KBtu/h
Check whether the connecting 
wiring between main board and the 
IPM module is connected tightly.
Yes
Yes
No
Check whether the 
input power supply is 
correct? 208-230V, 
1PH, 60Hz
No
No
Correct the incoming 
power problem, then 
check whether the sys-
tem operates normally
Check whether the 
power supply line is 
connected correctly 
and tightly.
No
Connect it cor-
rectly and tightly, 
check ok or not?
Yes
No
Check whether 
the lines in E-part 
box are connected 
tightly.
No
Connect it tightly, 
check ok or not?
NoYes
Check whether the bridge recti-
ers are normal? Use the multi-
meter to measure the resistance 
between each two terminals, 
check whether there is the condi-
tion that value of resistance is 0.
Replace the 
bridge rectiers.
No
Yes
Check whether the wir-
ing of each reactor is 
correct? Check whether 
the PFC module broken.
Replace the 
wiring or reactor 
or replace the 
PFC module(for 
M4OC-
36HRFN1-M)
No
No
Connect it 
tightly, unit oper-
ates correctly?
No
Yes
Replace the IPM 
module, check 
whether the system 
works normally.
No
Check if the outdoor 
fan runs properly 
or the outdoor unit 
ventilation is good.
For AC fan models, 
check whether the 
resistance of the fan 
motor is normal. If not, 
replace the fan motor. 
For DC fan models, re-
fer to the solution of fan 
speed malfunction (E8) 
. Find out the cause 
and repair it.
Yes
No
Replace the main board; 
check whether the sys-
tem operates normally?
No
Yes
Replace the compressor, 
check whether the sys-
tem operates normally?
Problem Solved
Yes
Yes
Yes
Check whether the connecting wiring 
to the compressor is connected cor-
rectly and tightly
Connect it 
tightly, check ok 
or not?
No
Yes