Troubleshooting SiUS04-904
Service Diagnosis 105
4.5 Thermistor or Related Abnormality (Indoor Unit)
Remote
Controller
Display
C4, C9
Method of
Malfunction
Detection
The temperatures detected by the thermistors are used to determine thermistor errors.
Malfunction
Decision
Conditions
When the thermistor input is more than 4.96 V or less than 0.04 V during compressor operation.
(reference)
When above about 414°F (212°C) (less than 120 ) or below about –58°F (–50°C) (more than
1,860 k).
Note: The values vary slightly in some models.
Supposed
Causes
Faulty connector connection
Faulty thermistor
Faulty PCB
Troubleshooting
Check No.06
Refer to P.146
C4 : Heat exchanger thermistor
C9 : Room temperature thermistor
YES
(R7134)
NO
Check No. 06
Check the thermistor resistance
value.
YES
NO
Caution
Be sure to turn off the power switch before connecting or disconnecting
the connector, or parts damage may occur.
Correct the connection.
Replace the thermistor.
(Replace the indoor unit PCB.)
Replace the indoor unit PCB.
Is it normal?
Is it normal?
Check the connector connection.
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