Panasonic CS-E9SD3UAW Service Manual page 86

15.5.15 H99 (Indoor Freeze Prevention Protection: Cooling or Soft Dry)
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 35.6°F)
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 operates normally?
Check for 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?
NO
NO
NO
YES
NO
YES
For safety reason and to prevent
component breakdown, always switch
Caution
off the power before remove and
connect the component.
YES
Provide sufficient air passage
YES
Clean the air filter
YES
Clean the indoor unit heat exchanger
YES
Open the 2/3 way valve.
NO
Replace the indoor unit fan motor and/or
indoor unit PCB.
YES
Repair the pipe flare or union nuts
Reclaim and recharge refrigerant
YES
Reclaim and recharge with correct amount of
refrigerant.
NO
Replace the indoor pipe temperature sensor
Replace the indoor unit PCB
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