Panasonic CS-YE18NKV-6 Service Manual page 63

15.5.14 H99 (Indoor Freeze Prevention Protection: Cooling)
Malfunction Decision Conditions

Freeze prevention control takes place (when indoor pipe temperature is lower than 2°C)
Malfunction Caused

Clogged air filter of the indoor unit

Dust accumulation on the indoor unit heat exchanger

Air short circuit

Detection error due to faulty indoor pipe temperature sensor

Detection error due to faulty indoor unit PCB
Troubleshooting
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