Troubleshooting Flow - Mitsubishi Electric MUH-GA50VB-E1 Service Manual

10-4. Troubleshooting flow

Compressor and/or outdoor fan motor doesn't operate.
A A Check of outdoor unit
MUH-GA50VB
Operate the unit in COOL or HEAT mode by pressing the EMERGENCY OPERATION switch.
3-minute time delay works.
Test run operation operates for 30 minutes.
Compressor
doesn't operate.
Is there 5V DC between J205
the deicer P.C. board?
Is there 230V AC between 3 on the
compressor contactor (52C) and N
on the outdoor terminal block (TB1)?
Check the compressor and compressor
capacitor. Refer to 10-3.
Outdoor fan motor
doesn't operate.
Is there 5V DC between J205
the deicer P.C. board?
Check the outdoor fan motor.
Refer to 10-3.
No
+
–J101 – on
w
Yes
Replace the
No
deicer P.C.
board.
Yes
No
+
–J101 on –
w
Yes
Is there 230V AC between 4 on the
compressor contactor (52C) and
TAB20 on the deicer P.C. board?
Yes
Replace the
deicer P.C. board.
Is there 230V AC between 4 on the
compressor contactor (52C) and
TAB 20 on the deicer P.C. board?
Yes
Replace the
deicer P.C. board.
28
Rectify the indoor and
outdoor connecting wire.
No
No
Is there 230V AC between L–N on
the outdoor terminal block (TB1)?
w
Yes
Rectify the connecting wire.
Rectify the indoor and
outdoor connecting wire.
No
No
Is there 230V AC between L–N on
the outdoor terminal block (TB1)?
w
Yes
Rectify the connecting wire.
w Refer to 10-5.