Evaporator Temperature Sensor: Operation

WARNING: This page is about a different car, the 2005 Dodge Grand Caravan, 2005 Dodge Caravan, and 2005 Chrysler Town & Country. However, it is still accessible from the selected car via links, so may be relevant.

The evaporator temperature sensor monitors the temperature of the conditioned air once it passes through the A/C evaporator. The evaporator temperature sensor will change its internal resistance in response to the air temperatures it monitors and is connected to the A/C-heater control through sensor ground and signal circuits. As the conditioned air temperature increases, the resistance of the evaporator temperature sensor decreases and the voltage monitored by the A/C-heater control decreases. The external location of the evaporator temperature sensor allows the sensor to be removed or installed without disturbing the refrigerant in the A/C system.

The A/C-heater control uses this monitored voltage reading as an indication of the evaporator temperature. The A/C-heater control is programmed to respond to this input by sending electronic messages to the powertrain control module (PCM) over the controller area network (CAN) data bus. The PCM then cycles the A/C compressor clutch as necessary to optimize A/C system performance and to protect the A/C system from evaporator freezing.

The evaporator temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The evaporator temperature sensor is diagnosed using the DRBIII® scan tool. Refer to BODY DIAGNOSTIC PROCEDURES .