Si04-402A Troubleshooting
Service Diagnosis 79
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 212°C (less than 120 ohms) or below about –50°C (more than 1,860
kohms).
Note: The values vary slightly in some models.
Supposed
Causes
Faulty connector connection
Faulty thermistor
Faulty PCB
Troubleshooting
Check No.6
Refer to P.106
C4 : Indoor heat exchanger thermistor
C9 : Room temperature thermistor
Check the connector connection.
YES
Correct the connection.
Replace the thermistor.
(Replace the indoor unit PCB.)
Replace the indoor unit PCB.
Is it normal?
Is it normal?
(R1403)
NO
Check No. 6
Thermistor resistance check
YES
NO
Caution
Be sure to turn off power switch before connect or disconnect connector,
or parts damage may be occurred.
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