SiBE121135 Troubleshooting for SA Indoor Unit - FCQG, FFQ, FHQ, FDBQ, FBQ Series
Service Diagnosis 291
6.6 Thermistor or Related Abnormality (SA 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 If the cause of the problem is related to the thermistors, the thermistors should be checked prior
to changing the indoor unit PCB.
To check the thermistors, proceed as follows:
C4 : Indoor heat exchanger thermistor (R2T, R3T)
C9 : Room temperature thermistor (R1T)
Check No.01
Refer to P.325
Step Action
1 Disconnect the thermistor from the indoor unit PCB.
2 Read the temperature and the resistance value.
3
Check if the measured values correspond with the values in the table of thermistor
resistance check.
YES
(R14406)
NO
Check No. 01
Check the thermistor resistance
value.
YES
NO
Caution
Correct the connection.
Replace the thermistor.
(Replace the indoor unit PCB.)
Replace the indoor unit PCB.
Is it normal?
Is it normal?
Check the connection of
connectors.
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
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