Panasonic CS-RE18QKE Service Manual page 63

15.5.12 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
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