Evaporator Temperature Sensor / Switch: Description and Operation

A/C EVAPORATOR PROBE
The evaporator temperature sensor is a temperature sensing element located at the coldest point on the face of the evaporator. Output from the probe is sampled by the Powertrain Control Module. The evaporator temperature sensor is used to switch the A/C compressor clutch OFF before evaporator freeze-up occurs.

The A/C compressor clutch is switched OFF when the evaporator temperature sensor reaches 1.1 °C (34 °F). It is allowed to switch ON when the evaporator temperature sensor reaches 3.5 °C (40 °F). The evaporator temperature sensor prevents condensate water on the evaporator coil from freezing and obstructing A/C system air flow. The evaporator temperature sensor is non-repairable, and must be replaced if found faulty.