Air Conditioning Evaporative Temperature (ACET) Sensor

The ACET sensor monitors the evaporator air discharge temperature. The ACET sensor is a thermistor device in which resistance changes with temperature. The ACET sensor is used to more accurately control A/C clutch cycling, improve defrost/demist performance and reduce A/C clutch cycling. The electrical resistance of a thermistor decreases as the temperature increases, and the resistance increases as the temperature decreases. The PCM sources a low current 5 volts on the ACET circuit. With signal return (SIG RTN) also connected to the ACET sensor, the varying resistance affects the voltage drop across the sensor terminals. As the A/C evaporator air temperature changes, the varying resistance of the ACET sensor changes the voltage the PCM detects.