Panasonic Aquarea T-CAP R32 fault H99

What it means

During anti-freezing control in cooling operation, triggered when the indoor refrigerant liquid temperature is below 0°C, indicating risk of indoor coil freeze-up.

Likely causes

1. Low airflow across indoor heat exchanger
2. Refrigerant undercharge or restriction causing low evaporator temperature
3. Faulty water pump
4. Insufficient water flow rate in system
5. Clogged expansion valve or strainer
6. Refrigerant shortage (refrigerant leakage)
7. Faulty indoor refrigerant liquid temperature sensor
8. Heat pump error during normal operation triggers automatic switch to force mode
9. Flow switch fault or no flow detected
10. Vacuum pump oil backflow into charge hoses without proper prevention
11. Water pump circulation anti-freeze control insufficient to raise water temperature

Where to start

1. Verify indoor airflow is not restricted
2. Check error history for H99 record
3. Check the system water pump - Is the water pump working? If No, replace the faulty water pump.