Service Manual

Troubleshooting SiUS091133
103 Service Diagnosis
4.5 Thermistor or Related Abnormality (Indoor Unit)
Remote
Controller
Display
C4, C9
Method of
Malfunction
Detection
The temperatures detected by the thermistors determine thermistor errors.
Malfunction
Decision
Conditions
The thermistor input is more than 4.96 V or less than 0.04 V during compressor operation.
Supposed
Causes
 Disconnection of connector
 Defective thermistor
 Defective indoor unit PCB
Troubleshooting
Check No.01
Refer to P.142
C4 : Indoor heat exchanger thermistor
C9 : Room temperature thermistor
YES
(R15717)
NO
Check No. 01
Check the thermistor resistance
value.
YES
NO
Caution
Correct the connection.
Replace the thermistor.
Replace the indoor unit PCB.
Normal?
Normal?
Check the connection of
connectors.
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.