Panasonic WH-ADF0309J3E5CM Service Manual page 270

25.2.23 Indoor Freeze-up Protection (H99)
Error Code will not display (no Timer LED blinking) but store in EEPROM
Malfunction Decision Conditions

Freeze prevention control takes place (when indoor pipe temperature is lower than 2°C)
Malfunction Caused

Air short circuit at indoor unit

Clogged indoor unit air filter

Dust accumulation on the indoor unit heat exchanger

2/3 way valve closed

Faulty indoor unit fan motor

Refrigerant shortage (refrigerant leakage)

Clogged expansion valve or strainer

Faulty indoor pipe temperature sensor

Faulty indoor unit PCB
Troubleshooting
When abnormality indication starts again
Check the air passage
Is there any short circuit?
Check the indoor unit air filter
Is the air filter dirty?
Check the dust accumulation on the indoor unit heat
exchanger
Is the indoor unit heat exchanger dirty?
Check if 2/3 way valve is closed?
Check if indoor fan motor operated normally?
Check the gas leakage. Is Oil oozing out from the
2/3 way valve?
Check if expansion valve or strainer clogged
(ice formed)?
Check the indoor pipe temperature sensor
Does it conform to the sensor characteristic chart?
YES
YES
NO
YES
NO
YES
NO
NO
YES
YES
YES
NO
NO
YES
270
For safety reason and to prevent
component breakdown, always switch
Caution
off the power before remove and
connect the component.
● Provide sufficient air passage
● Clean the air filter
● Clean the indoor unit heat exchanger
● Open the 2/3 way valve.
● Replace the indoor unit fan motor and/or
indoor unit PCB.
● Repair the pipe flare or union nuts
● Reclaim and recharge refrigerant
● Reclaim and recharge with correct
amount of refrigerant.
● Replace the indoor pipe temperarure
sensor
● Replace the indoor unit PCB