Sensor-Evaporator Temperature: Operation

WARNING: This page is about a different car, the 2006 Dodge Magnum, 2006 Dodge Charger, and 2006 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

The evaporator temperature sensor is a thermistor that operates on a 5-volt reference signal sent out by the A/C-heater control. The sensor connects to the A/C-heater control through a two-wire lead and connector of the HVAC wire harness. The sensor monitors the temperature of the conditioned air downstream of the A/C evaporator and changes its internal resistance in response to changes in the air temperature. As the temperature increases, the sensor's resistance decreases which increases the reference signal voltage read by the A/C-heater control. As the temperature decreases, the sensor's resistance increases which decreases the reference signal voltage read by the A/C-heater control.

The A/C-heater control also uses the reference signal voltage as an indication that conditions are correct to request A/C operation, should the operator (manually) or the A/C-heater control (automatically) so desire this function. For the ATC system, the A/C-heater control broadcasts the A/C request on the controller area network (CAN) B bus, where it is read and processed by the front control module (FCM), which in turn broadcasts it on the CAN C bus, where it is read and processed by the powertrain control module (PCM). For the MTC system, the A/C-heater control sends the request for A/C to the CCN via a dedicated mux circuit. The CCN then broadcasts the A/C request on the CAN B bus, where it is read and processed by the FCM, which in turn broadcasts it on the CAN C bus, where it is read and processed by the PCM.

The evaporator temperature sensor is diagnosed using a scan tool (HEATING AND A/C SYSTEMS and to HVAC - ELECTRICAL DIAGNOSTICS for more information.

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