Mitsubishi Electric MUZ-FA25VA-E1 Service Manual page 33

11-6. Troubleshooting flow
When POWER lamp flashes 5-time.
Outdoor unit does not operate.
How to check inverter/ compressor
A
Disconnect the connector (CN61)
between compressor and the
intelligent power module (IPM).
Check the voltage
between terminals.
No
Are the voltages
balanced?
Yes
Check the
compressor.
Check of open phase
B
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 115V
<< Operation method>>
Start cooling or heating operation by pressing EMERGENCY OPERATION
switch on the indoor unit. (Test run operation : 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 inverter P.C. board flashes 9 times.
Check of intelligent power module
C
Measure the resistance between the terminals on the intelligent
power module.
<<Measurement point>>
at 6 points
BLK-WHT, WHT-BLK
BLK-RED, RED-BLK
WHT-RED, RED-WHT
<<Judgement>>
Infinite ["]···········Normal
0~dozens of ······Abnormal (short)
See 11-6.B "Check of open phase" .
Check the resistance of the intelligent
power module.
See 11-6.D "Check of compressor" .
w Measure AC voltage between
the lead wires at 3 points.
See 11-6.C "Check of intelligent power module".
Is the resistance
infinite?
No
(0~several
9-time flash
ohmmeter indication
"
X1
"
X1
33
Yes
Replace the inverter P.C.
board.
"
)
Replace the inverter P.C.
board and compressor.
Inverter P.C. board
(Parts side)
LED
2.5-second OFF
Normal
(infinite)
Abnormal
(0~dozens of ")
Flashing