Mitsubishi Electric Mr.Slim MUZ-FD09NA Service Manual page 26

I Check of outdoor fan motor
Disconnect CN932 from the inverter P.C. board, and
measure the resistance of the outdoor fan motor.
Is the outdoor fan motor normal?
(Refer to 10-4.)
Replace the inverter P.C. board.
J Check of power supply
Disconnect the connector (CN61)
between compressor and intelligent
power module.
Turn ON power supply and press
EMERGENCY OPERATION switch.
Does POWER lamp on the indoor
unit light up?
Yes
Is there voltage 280 ~ 370 VDC
between DB61 (+) and DB61 (–) on
the inverter P.C. board?
(Refer to 10-6.1.)
No
Check the electric parts in main circuit.
Yes
Is there voltage 208/230 VAC
between the indoor terminal
No
block S1 and S2?
Dose LED on the inverter P.C.
board light up or fl ash? (Refer
Yes
to 10-6.1.)
Replace the outdoor fan motor.
No
Rectify indoor/outdoor
connecting wire.
Yes
Yes
If light up, OK.
If fl ash, refer to 10-3.
26
Replace the indoor
electronic control P.C.
No
board.
Replace the inverter
No
P.C. board.
280 ~ 370 VDC
DB61
Inverter P.C. board
(Solder side)