77
15.5.21 F90 (Power Factor Correction Protection)
Malfunction Decision Conditions
To maintain DC voltage level supply to power transistor.
To detect high DC voltage level after rectification.
Malfunction Caused
During startup and operation of cooling and heating, when Power Factor Correction (PFC) protection circuitry at
the outdoor unit main PCB senses abnormal DC voltage level for power transistors.
When DC voltage detected is LOW, transistor switching will turn ON by controller to push-up the DC level.
When DC voltage detected is HIGH (391Vdc – 425Vdc), active LOW signal will send by the controller to turn OFF
relay RY-C.
Troubleshooting
YES
NO (391.2Vdc ~ 425Vdc)
NO
When abnormality indication starts again
Reset the error code and turn on the unit again
Is AC power supply normal fluctuation? ● AC power supply abnormal surge
● Defect in PFC circuitry
● Replace the outdoor unit PCB
YES (~280Vdc)
● Defect in outdoor fan motor
● Replace outdoor fan motor
NO
● Defect in compressor
● Replace compressor
NO
● Defect in reactor
● Replace reactor
YES
YES
Verify PFC abnormality by measuring DC voltage between
DCP(+) and DCN(-) at the capacitor PCB
Is the DC voltage between DCP(+) and DCN(-) normal?
Confirm the DC voltage between CN-FM 1 and 4 when
compressor is running. Normal voltage range should be
between 265-325Vdc
YES
Is the DC voltage between CN-FM1 and 4 of the outdoor fan
motor normal?
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, U-W)
uniform?
Check the reactor impedance
Is the impedance of the reactor low?
For safety reason and to prevent
component breakdown, always switch
off the power before remove and
connect the component.
Caution
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