Service diagnosis
33
Domestic air conditioner
10.4.1 Thermistor or Related Abnormality
Indoor Display E1: Room temperature sensor failure
E2: Heat-exchange sensor failure
outdoor display F21 LED1 flash 10 times˖Defrost temperature sensor failure
F7 LED1 flash 11 times˖Suction temperature sensor failure
F6 LED1 flash 12 times˖Ambient temperature sensor failure
F25 LED1 flash 13 times˖Discharge temperature sensor failure
The temperatures detected by the thermistors are used to determine thermistor errors
when the thermistor input is more than 4.92V or less than 0.08V during compressor
operation.
z Note: The values vary slightly in some models
Ŷ Faulty connector connection
Ŷ Faulty thermistor
Ŷ Faulty PCB
Troubleshooting * Caution Be sure to turn off power switch before connect or disconnect connector, or
else parts damage may be occurred.
Thermistor resistance check method:
Remove the connector of the thermistor on the PCB, and measure the resistance of thermistor using tester. The
relationship between normal temperature and resistance is shown in the value of indoor thermistor.
Thermistor resistance check
Is it normal?
Yes
NO
Yes
Is it normal?
NO
Check the connector connection.
Replace the thermistor
Replace the indoor unit PCB
Correct the connection
Method of
Malfunction
Malfunction
Detection
Conditions
Troubleshooti
ng
Supposed
Causes
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