Panasonic 2WAY Multi Technical & Service Manual page 175

● If communication error occurs, check the sensor's ground fault.
● Check sensors (thermistor) ground fault.
Before checking, turn off the device and remove target sensor from the board before performing measurement.
6
Ground fault check
6-1
6-2
Measure the resistance between one end of the indoor/outdoor control wire
and the point of ground screw, as well as the resistance between the other
operating line end and the point of the ground screw. Are both measured
resistance values in MΩ unit (infi nite)?
Replace thermistor and wiring
V–56
Yes Good
No 6-2