Troubleshooting Flow - Mitsubishi Electric MUZ-GL12NA Service Manual

10-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor
Disconnect the connector between the compressor
and the power module (IC700) (MUZ-GL09/12/15/18,
MUY-GL09/12/15/18)/IGBT module (IC700) (MUZ-
GL24, MUY-GL24).
Check the voltage between terminals.
Are the voltages balanced?
Yes
Check the compressor.
B Check of open phase
● With the connector between the compressor and the power module (IC700) (MUZ-GL09/12/15/18, MUY-GL09/12/15/18)/IGBT
module (IC700) (MUZ-GL24, MUY-GL24) disconnected, activate the inverter and check if the inverter is normal by measuring
the voltage balance between the terminals.
Output voltage is 50 - 130 V. (The voltage may differ according to the tester.)
<< Operation method>>
Start cooling or heating operation by pressing EMERGENCY OPERATION switch on the indoor unit. (TEST RUN OPERA-
TION: Refer to 7-6.)
<<Measurement point>>
At 3 points
*Measure AC voltage between the lead wires at 3 points.
BLK (U)-WHT (V)
BLK (U)-RED (W)
WHT(V)-RED (W)
NOTE: 1. Output voltage varies according to power supply voltage.
2. Measure the voltage by analog type tester.
3. During this check, LED of the inverter P.C. board blinks 9 times. (Refer to 10-6.1.)
C Check of compressor
Refer to 10-5. "Check of compressor
winding".
Is the compressor normal?
Yes
Refer to 10-5. "Check of compressor
operation time".
Does the compressor operate continuously?
Yes
OK
OBH733J
See 10-5. "Check of open phase".
Replace the inverter P.C. board.
No
See 10-5. "Check of compressor".
Replace the compressor.
No
Refer to 10-5. "Check of compressor start failure".
No
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