Panasonic WH-UD05JE5 Service Manual page 215

19.5.26 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).
Troubleshooting:
Check the system water pump.
Is the water pump working?
Yes
Check the system water
flow rate.
Is the water pump speed
adjusted according to system
hydraulic external static pressure?
Yes
Check the system water passage.
Is there any water leakage?
No
Check the 2 way valve.
Is the 2 way valve partially
closed?
No
Caution
Replace the faulty water
No
pump.
No
Readjust the water
pump speed.
Yes
Fix the system water
leakage.
Yes
Open the 2 way valve.
For safety reason and to prevent component breakdown,
always switch off the power before remove and connect the component.
Check for clogged
expansion valve or strainer.
Is the expansion valve or
strainer clogged (ice formed)?
No
Check refrigerant amount.
Is the additional refrigerant
amount filled correctly?
Yes
Check the indoor refrigerant
liquid temperature sensor.
Does it conform to the sensor
characteristic chart?
Yes
No
215
- Replace the expansion
Yes
valve and/or strainer.
- Reclaim and recharge
refrigerant.
No
Reclaim and recharge with
correct amount of refrigerant.
Replace the indoor unit PCB
(main).
Replace the indoor refrigerant
liquid temperature sensor.