Evaporator Temperature Sensor: Operation

WARNING: This page is about a different car, the 2004 Dodge Pickup and 2004 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The evaporator temperature sensor monitors the temperature of the evaporator. The sensor will change its internal resistance in response to the temperatures it monitors. The A/C-heater control module is connected to the sensor through a sensor ground circuit and a sensor signal circuit. As the evaporator temperature increases, the resistance of the sensor decreases and the voltage monitored by the module decreases. The module uses this monitored voltage reading to an indication of the evaporator temperature. The A/C-heater control module is programmed to respond to this input by cycling the air conditioning compressor clutch as necessary to optimize air conditioning system performance and to protect the system from evaporator freezing. The external location of the sensor allows the sensor to be removed or installed without disturbing the refrigerant in the system. The evaporator temperature sensor is diagnosed using a DRBIII® scan tool. Refer to BODY DIAGNOSTIC PROCEDURES .