Panasonic CS-MZ16VKE Service Manual page 103

17.4.21 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
103