Troubleshooting Flow - Mitsubishi Electric SUZ-KA25VA Technical & Service Manual

12-5. Troubleshooting flow

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 compressor and the intelligent power
module disconnected, activate the inverter and check if the inverter
is normal by measuring the balance of voltage between terminals.
Output voltage [V]
115V
<< Operation method>>
Start cooling or heating operation by pressing the EMERGENCY OPERATION switch
on the indoor unit. (test-run mode : refer to page 24 for SLZ/SUZ and 30 for SEZ/SUZ.)
<<Measurement point>> w 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 inverter P.C. board flashes 9 times.
Check of intelligent power module
C
Measure the resistance between 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)
[SUZ-KA25VA.TH SUZ-KA35VA.TH SUZ-KA25VAH.TH SUZ-KA35VAH.TH]
See B "Check of open phase".
Check the resistance of the intelligent
power module.
D "Check of compressor".
See
See C 'Check of intelligent power module'.
Yes
Is the resistance
infinite?
No
"
(0~several
9-time flash
ohmmeter indication
"
X1
"
X1
62
Replace the inverter P.C.
board.
)
Replace the inverter P.C.
board and compressor.
Inverter P.C. board
Flashing
LED
2.5-second OFF
Normal
(infinite)
Abnormal
(0~dozens of ")