Evaporator Temperature Sensor / Switch: Description and Operation

Freeze-up Control = Fin sensor - 3 wire = input to PCM, evaporator mounted, cycles off below 34°F, cycles back on above 45 °F

SYSTEM OPERATION
Evaporator Probe
The evaporator probe can be replaced without having to remove the unit housing from the vehicle.

The evaporator probe is located in the unit housing and placed in the evaporator fins. The probe prevents evaporator freeze-up. This is done by cycling the compressor clutch OFF when evaporator temperature drops below freeze point. It cycles ON when the evaporator temperature rises above freeze point. The evaporator probe uses a thermistor probe in a capillary tube. The tube is inserted between the evaporator fins in the heater-A/C unit housing.