Troubleshooting Flow; A How To Check Inverter/Compressor - Mitsubishi Electric Mr.Slim MUZ-GC25NA - C1 Service Manual

9-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor

MUZ-GC25/35NA MUZ-GC50NA-
Disconnect the connector (CN61)
between compressor and the intel-
ligent power module (IPM).
Check the voltage
between terminals.
Are the voltages
balanced?
No
Yes
Check the compres-
sor.
MUZ-GC50NA- MUZ-GC60/71NA
C1
Disconnect the terminal of the compressor. 3 minutes after turn-
ing on the power supply, start EMERGENCY OPERATION.
Measure the voltage between each lead wire lead-
ing to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Is voltage output on right table?
Is output balanced?
Is the input voltage to the outdoor electronic control
P.C. board 370 V or more?
Turn off power supply of indoor and outdoor unit, and
measure the compressor winding resistance between
the compressor terminals.
Is the resistance between each terminal normal?
Reconnect the lead wire of compressor, and turn on power
supply to indoor and outdoor unit.
3 minutes later, starts EMERGENCY OPERATION.
Clarify the causes by counting time until the inverter stops.
0 to 10 seconds: compressor rare short
10 to 60 seconds: compressor lock
60 seconds to 5 minutes: refrigerant circuit defective
5 minutes or more: normal
C2
See 9-5. "Check of open phase" .
Replace the inverter P.C. board.
See 9-5. "Check of compressor" .
Yes
Yes
Yes
Yes
After the outdoor fan starts running, wait for 1 minute or more before measuring
the voltage.
Output voltage is 50 - 130 V. (The voltage may differ according to the tester.)
No
No
Replace the power board.
No
No
Replace the compressor.
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