Evaporator Temperature Sensor / Switch: Description and Operation

Prevention of evaporator freeze-up is controlled by a 3 wire fin sensor that is mounted to the evaporator. The sensor provides a temperature input to the PCM which cycles the compressor clutch off below 34 °F, and cycles back on above 45 °F.

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.