Troubleshooting SiMT041311E139 Service Diagnosis2.12 Thermistor or Related Abnormality (Indoor Unit)Error Code C4, C9Method of ErrorDetectionThe temperatures detected by the thermistors determine thermistor errors.Error DecisionConditionsThe thermistor input is 4.96 V and more or 0.04 V and less during compressor operation.SupposedCauses Disconnection of connector Thermistor corresponding to the error code is defective. Defective indoor unit PCB (A1P, A4P)TroubleshootingCheck No.01Refer to P.181C4 : Indoor heat exchanger thermistorC9 : Room temperature thermistorYES(R19725)NOCheck No. 01Check the thermistor resistancevalue.YESNOCautionCorrect the connection.C4: Replace the indoor heatexchanger thermistor.C9: Replace the humiditysensor PCB (A4P).Replace the control PCB(A1P).Normal?Normal?Check the connection ofconnectors.Be sure to turn off the power switch before connecting or disconnectingconnectors, or parts may be damaged.∗ To secure the connection,once disconnect the connectorand then reconnect it.
