Evaporator Temperature Sensor / Switch: Description and Operation

EVAPORATOR PROBE
The evaporator probe is a 2 wire temperature sensing element located at the coldest point on the face of the evaporator. The switch is attached to the evaporator coil with the sensing probe inserted into the coil fins. The evaporator temperature probe prevents condensate water on the evaporator coil from freezing and obstructing A/C system air flow.

The probe is used to switch the clutch OFF before evaporator freeze-up occurs. Output from the probe is sampled by the Body Control Module. The clutch is switched OFF when the probe temperature reaches 1.1 °C (34 °F). It is allowed to switch ON when the probe temperature reaches 2.2 °C (36 °F).