Panasonic CS-PS9NKH Service Manual page 75

14.4.12 H99 (Indoor Freeze Prevention Protection: Cooling or Soft Dry)
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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