Panasonic WH-MHF09G3E5 Service Manual page 109

16.5.25 Output Over Current Detection (F23)
Malfunction Decision Conditions:
During operation of heating, when outdoor DC current is above 40.1 ± 5.0A (for: UD07~09CE) OR 44.7 ± 5.0A
(for: UD12~16CE) is detected by the IPM DC Peak sensing circuitry in the outdoor unit PCB (main).
Malfunction Caused:
1 Faulty outdoor unit PCB (main).
2 Faulty compressor.
Abnormality Judgment:
Continue for 7 times.
Troubleshooting:
Check the compressor winding resistance:
- Turn OFF the power and disconnect the
harnesses U, V, and W.
- Measure the winding resistance between
U-V, V-W, and W-U.
Checking the power transistor
Never touch any live parts for at least 10 minutes after turning off the circuit breaker.
If unavoidably necessary touch a live part, make sure the power transistor's supply
voltage is below 50 V using the tester.
For the UVW, make measurements at the Faston terminal on the board or the relay
connector.
Power transistor
Tester's negative terminal
(+)
UVW
Tester's positive terminal
Normal resistance
Abnormal resistance
For safety reason and to prevent component breakdown,
always switch off the power before remove and connect the component.
Are the compressor's
winding resistance (U-V, V-
W, or U-W) shorted?
No
Power transistor
UVW
(-)
Power transistor
Power transistor
UVW
(+)
Several kohms to several Mohms
0 or ∞
109
- Compressor defective due to
Yes
winding shorted.
- Replace the compressor.
- Outdoor eletronic circuit
defect due to power transistor
shorted.
- Replace the outdoor unit
PCB (main).
UVW
(-)