Cabin Temperature Sensor / Switch: Testing and Inspection

Flowchart-In-car Temperature Sensor (Part 1 Of 2):

Flowchart-In-car Temperature Sensor (Part 2 Of 2):

Self-diagnosis indicator light A comes on: Indicates a problem in the in-car temperature sensor circuit. Use a digital multimeter (KS-AHM-32-003) to check it.

The in-car temperature sensor is a temperature dependent resistor (thermistor). The resistance of the thermistor decreases as the temperature inside the vehicle increases.

In-car Temperature Sensor-Test:

In-car Temperature Sensor-Test:

Compare the resistance reading between the No. 1 and No. 2 terminals of the in-car temperature sensor with specifications shown in the graph: It should be within specification.

CAUTION: The sensor uses a thermistor which can be damaged if high current is applied to it during testing. Therefore, use a circuit tester that puts out a measuring current of 1 mA or less.