A How To Check Inverter/Compressor - Mitsubishi Electric MUZ-GB50VA Service Manual

11-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor

MUZ-GB50VA-
/
E1
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
MUZ-GB50VA-
E3
Disconnect the connector (CN61) between
compressor and the intelligent power module
(IPM).
Check the voltage between terminals.
Are the voltages balanced?
Check the compressor.
E2
Yes
Yes
Yes
Yes
No
Yes
• After the outdoor fan starts running, wait for 1 minute or more before
measuring the voltage.
• The output voltage values have the tolerance of ±20%.
No
No
Replace the power board.
No
No
Replace the compressor.
See 11-5. "Check of open phase".
Replace the inverter P.C. board.
See 11-5. "Check of compressor".
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