Mitsubishi Electric Mr.Slim MUZ-A09NA Service Manual page 48

B Check of open phase
MUZ-A09/12/15/17 MUY-A15/17
● 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 OPERATION: Refer to 7-7.)
<<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 fl ashes 9 times. (Refer to 10-6.1.)
C Check of intelligent power module
MUZ-A09/12/15/17 MUY-A15/17
●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>>
Infi nite [Ω]············Normal
0 - dozens of········Abnormal (short)
D Check of compressor
MUZ-A09/12/15/17 MUY-A15/17
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.
E Check of compressor winding
MUZ-A09/12/15/17 MUY-A15/17
● Disconnect the connector (CN61) between the compressor and intelligent power module, and measure the resistance be-
tween the compressor terminals.
<<Measurement point>>
At 3 points
BLK-WHT
BLK-RED
WHT-RED
<<Judgement>>
Refer to 10-4.
0 [Ω] ················Abnormal (short)
Infinite [Ω] ·······Abnormal (open)
NOTE: 1. Be sure to zero the ohmmeter before measurement.
2. Winding resistance for each phase at 68°F (20°C).
Refer to "3. SPECIFICATION".
Replace the compressor.
No
No
Measure the resistance between the lead wires at 3 points.
9-time flash
Is the compressor operation
time more than 10 seconds?
Yes
Check the refrigerant circuit.
48
Inverter P.C. board
(Parts side)
Flashing
LED
2.5-second OFF
ohmmeter indication
Ω
••••••Normal
(infinite)
X1
Ω
••••••Abnormal
(0~dozens of Ω)
X1
Replace the compressor.
No