Troubleshooting for SA Indoor Unit SiBE121135_A195 Service Diagnosis6.6 Thermistor or Related Abnormality (SA Indoor Unit)Error Code C4, C5, C9Method of ErrorDetectionThe temperatures detected by the thermistors determine thermistor errors.Error DecisionConditionsThe thermistor input is more than 4.96 V or less than 0.04 V during compressor operation.SupposedCauses Disconnection of connector Defective thermistor corresponding to the error code Defective indoor unit PCBTroubleshooting If the cause of the problem is related to the thermistors, the thermistors should be checked priorto changing the indoor unit PCB.To check the thermistors, proceed as follows:C4 : Indoor heat exchanger thermistor 1 (liquid pipe) (R2T)C5 : Indoor heat exchanger thermistor 2 (R3T)C9 : Room temperature thermistor (R1T)Check No.01Refer to P.230 Step Action1 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 thermistorresistance check.YES(R14406)NOCheck No. 01Check the thermistor resistancevalue.YESNOCautionCorrect the connection.Replace the thermistor.(Replace the indoor unit PCB.)Replace the indoor unit PCB.Is it normal?Is it normal?Check the connection ofconnectors.Be sure to turn off the power switch before connecting or disconnectingconnectors, or parts may be damaged.
