Panasonic WH-MXF09D3E8 Service Manual page 83

16.5.14 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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