Panasonic CS-XZ20XKEW-H Service Manual page 124

18.4.13 H33 (Unspecified Voltage between Indoor and Outdoor)
Malfunction Decision Conditions

The supply power is detected for its requirement by the indoor/outdoor transmission.
Malfunction Caused

Wrong models interconnected.

Wrong indoor unit and outdoor unit PCBs used.

Indoor unit or outdoor unit PCB defective.
Troubleshooting
124