Panasonic CS-PS12JKT, Service Manual, Page: 66 / 79

66
14.4.23 F99 (Output Over Current Detection)
Malfunction Decision Conditions
During operation of cooling and heating, when an output over-current (18.5A) is detected by checking the current that
flows in the inverter DC peak sensing circuitry.
Malfunction Caused
•
DC peak due to compressor failure.
•
DC peak due to defective power transistor(s).
•
DC peak due to defective outdoor unit PCB.
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 Power transistor (+) UVW Power transistor (-) UVW
Tester’s positive terminal UVW Power transistor (+) UVW Power transistor (-)
Normal resistance Several k Ω to several M Ω
Abnormal resistance 0 or ∞
Check the compressor winding resistance:
•
Turn off the power and disconnect
the harness U, V and W
•
Measure the winding resistance
between U-V, V-W and W-U.
When F99 indication happens For safety reason and to prevent component
breakdown, always switch off the power
before remove and connect the component.
Get restarted and measure the input
current.
NO
Input current > 18.5A?
•
Replace the outdoor unit PCB.
NO
YES
Are the compressor’s winding resistance
(U-V, V-W or U-W) shorted?
•
Compressor defective due to winding
shorted.
•
Replace compressor
•
Outdoor electronic circuit defect due
to power transistor short
•
Replace the outdoor unit PCB.
YES