Mitsubishi Electric Mr.Slim MUZ-A17NA, Service Manual, Page: 47 / 84

47
10-5. Troubleshooting flow
MUZ-A09/12/15/17 MUY-A15/17
MUZ-A24 MUY-A24 MUZ-GA24 MUY-GA24
Check the voltage
between terminals.
Check the compres-
sor.
Disconnect the connector (CN61)
between compressor and the intel-
ligent power module (IPM).
Check the resistance of the intelligent
power module.
See 10-5. “Check of compressor” .
No
See 10-5. “Check of open phase” .
See 10-5. “Check of intelligent power module”.
Is the resistance
infinite?
Yes
Replace the inverter P.C.
board.
No
(0 - several
Ω )
Yes
Is the voltage
balanced?
Replace the inverter P.C.
board and compressor.
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?
Yes
No
Disconnect the terminal of the compressor. 3 minutes after turning
on the power supply, start EMERGENCY OPERATION.
After the outdoor fan starts running, wait for 1 minute or more before measur-
ing the voltage.
Output voltage is 50 - 130 V. (The voltage may differ according to the tester.)
Is output balanced?
Yes
No
Is the input voltage to the outdoor electronic control
P.C. board 370 V or more?
Yes
No
Replace the power board.
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?
Yes
No
Replace the compressor.
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 layer short
10 to 60 seconds: compressor lock
60 seconds to 5 minutes: refrigerant circuit defective
5 minutes or more: normal
A How to check inverter/compressor