Panasonic CS-E12RB4UW Service Manual page 77

15.4.17 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.
Reset the error code and turn on the unit again.
Is AC power supply normal fluctuation?
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.
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?
YES
NO (391.2Vdc ~ 425Vdc)
YES
YES
77
NO
AC power supply abnormal surge.
YES (~280Vdc)
Defect in PFC circuitry.
Replace the outdoor unit PCB.
NO
Defect in outdoor fan motor.
Replace outdoor fan motor.
For safety reason and to prevent
component breakdown, always switch
Caution
off the power before remove and
connect the component.
NO
Defect in compressor.
Replace compressor.
Defect in reactor.
Replace reactor.