Panasonic CS-E18SD3UAW service manual - Page 88

15.5.17 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? YES Verify PFC abnormality by measuring DC voltage between DCP(+) and DCN(-) at the capacitor PCB NO AC power supply abnormal surge Is the DC voltage between DCP(+) and DCN(-) normal? NO (391.2Vdc ~ 425Vdc) Confirm the DC voltage between CN-FM 1 and 4 when compressor is running. Normal voltage range should be between 265-325Vdc YES (~280Vdc) Defect in PFC circuitry Replace the outdoor unit PCB Is the DC voltage between CN-FM1 and 4 of the outdoor fan NO motor normal? Defect in outdoor fan motor Replace outdoor fan motor 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 YES Caution For safety reason and to prevent component breakdown, always switch off the power before remove and connect the component. NO Defect in compressor Replace compressor Is the impedance of the reactor low? YES Defect in reactor Replace reactor 88