Panasonic CS-E7NKR Service Manual page 138

16.4.29 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 (+)
138
UVW Power transistor (-)
UVW
Several kΩ to several MΩ
0 or ∞
UVW
Power transistor (-)