Panasonic CS-MRE7MKE Service Manual page 77

17.4.25. F99 (Output Over Current Detection)
Malfunction Decision Conditions
During operation of cooling and heating, when an output over-current (DC peak current value at IPM Prevention Control) is
detected by checking the current that flows in the inverter DC peak sensing circuitry.
Malfunction Caused
• Faulty outdoor unit PCB
• Faulty compressor
Troubleshooting
• Checking the power transistor
• Never touch any live parts for at least 10 minutes after turning off the circuit breaker.
• If unavoidable necessary to touch a live part, make sure the power transistor's supply voltage is below 50V using the tester.
• For the UVW, make measurement at the Faston terminal on the board of the relay connector.
Tester's negative terminal
Tester's positive terminal
Normal resistance
Abnormal resistance
Power transistor (+)
UVW Power transistor (+)
UVW Power transistor (-)
UVW
Several k to several M
0 or
77
UVW
Power transistor (-)