Mitsubishi Electric MSZ-FD VA Series Service Manual page 41

B Check of open phase
MUZ-FD25/35
● With the connector between the compressor and the intelligent power module disconnected, activate the inverter and check if
the inverter is normal by measuring the balance of voltage 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 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
MUZ-FD25/35
Refer to 11-5. "Check of compressor
winding".
Is the compressor normal?
Yes
Refer to 11-5. "Check of compressor
operation time".
Does the compressor operate continuously?
Yes
OK.
Measure AC voltage between the lead wires at 3 points.
No
No
Replace the compressor.
Refer to 11-5. "Check of compressor start failure".
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