Panasonic WH-MHF12G9E8 Service Manual page 105

16.5.17 Indoor Freeze-up Protection (H99)
Malfunction Decision Conditions:
During anti-freezing control in cooling operation, when the indoor refrigerant liquid temperature < 0°C.
Malfunction Caused:
1 Faulty water pump.
2 Insufficient water flow rate in system.
3 Water leak in system.
4 2 way valve partially closed.
5 Clogged expansion valve or strainer.
6 Refrigerant shortage (refrigerant leakage).
7 Faulty indoor refrigerant liquid temperature sensor.
8 Faulty indoor unit PCB (main).
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