A How To Check Inverter/Compressor - Mitsubishi Electric MUZ-FH25VEHZ Service Manual

11-5. TROUBLESHOOTING FLOW

A How to check inverter/compressor

Disconnect the connector between the compressor
and the power module (IC700) (MUZ-FH25/35)/IGBT
module (IC700) (MUZ-FH50).
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-FH25/35)/IGBT module (IC700) (MUZ-FH50)
disconnected, activate the inverter and check if the inverter is normal by measuring the voltage balance between the termi-
nals.
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 8-3.)
<<Measurement point>>
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 fl ashes 9 times. (Refer to 11-6.1.)
C Check of compressor
Refer to 11-5. "Check of compressor
winding".
Is the compressor normal?
Refer to 11-5. "Check of compressor
operation time".
Does the compressor operate continuously?
OK.
OBH625A
No
Measure AC voltage between the lead wires at 3 points.
No
Yes
No
Yes
See 11-5. "Check of open phase".
Replace the inverter P.C. board.
See 11-5. "Check of compressor".
Replace the compressor.
Refer to 11-5. "Check of compressor start failure".
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