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16.4.21 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
When abnormality indication starts again.
YES
NO (391.2Vdc ~ 425Vdc)
YES
YES
NO
NO
NO
For safety reason and to prevent
component breakdown, always switch
off the power before remove and
connect the component.
Replace the outdoor unit PCB.
Defect in PFC circuitry.
Replace outdoor fan motor.
Defect in outdoor fan motor.
Replace compressor.
Defect in compressor.
Replace reactor.
Defect in reactor.
AC power supply abnormal surge.
Reset the error code and turn on the unit again.
Is AC power supply normal fluctuation?
Is the DC voltage between DCP(+) and DCN(-) normal?
Check the reactor impedance.
Is the impedance of the reactor low?
Verify PFC abnormality by measuring DC voltage between
DCP(+) and DCN(-) at the capacitor PCB.
Is the DC voltage between CN-FM1 and 4 of the outdoor fan
motor normal?
Are the compressor’s winding resistance (U-V, V-W, U-W)
uniform?
Confirm the DC voltage between CN-FM 1 and 4 when
compressor is running. Normal voltage range should be
between 265-325Vdc.
Turn off the power and disconnect the harnesses U, V,
and W.
Check the compressor winding resistance:
Measure the winding resistance between U-V, V-W and
W-U.
YES (~280Vdc)
Caution
