Evaporator Temperature Sensor / Switch: Description and Operation

Air Conditioning Evaporator Temperature Sensor

A/C Evaporator Temperature (ACET) Sensor Voltage And Resistance Chart, Part 1:

A/C Evaporator Temperature (ACET) Sensor Voltage And Resistance Chart, Part 2:

The Air Conditioning Evaporative Temperature (ACET) sensor senses evaporator air discharge temperature. The ACET sensor is a thermistor device in which resistance changes with temperature. The electrical resistance of a thermistor decreases as the temperature increases, and increases as the temperature decreases. The PCM sources a low current 5 volts on the ACET circuit. With SIG RTN also connected to the ACET sensor, the varying resistance affects the voltage drop across the sensor terminals. As A/C evaporator air temperature changes, the varying resistance of the ACET sensor changes the voltage the PCM detects.

The ACET sensor is used to more accurately control A/C clutch cycling, improving defrost/demist performance, reduce A/C clutch cycling, etc.