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15.2.23 F99 (Outdoor Direct Current (DC) Peak Protection)
Malfunction Decision Conditions
During operation of cooling and heating, when an output over-current 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.
Abnormality Judgment:
Continuous happen for 7 times.
Troubleshooting
Tester’s negative terminal Power transistor (+) UVW Power transistor (-) UVW
Tester’s positive terminal UVW Power transistor (+) UVW Power transistor (-)
Normal resistance Several kΩ to several MΩ
Abnormal resistance 0 or ∞
Input current > 18.5A?
Yes
Get restarted and
measure the input
current.
Yes
No
Replace the outdoor unit
PCB.
No
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
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
Is the refrigerant over
charged?
Yes
Remove excess gas
No
For safety reason and to prevent component
breakdown, always switch off the power
before remove and connect the component.
■ Checking the power transistor
● Never touch any live parts for at least 10 minutes after turning off the circuit breaker.
● If unavoidably necessary to 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.
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