Operation

OPERATION

The evaporator temperature sensor monitors the surface temperature of A/C evaporator and supplies an input signal to the A/C-heater control. The A/C-heater control uses the evaporator temperature sensor input signal to optimize A/C system performance and to protect the A/C system from evaporator freezing. The evaporator temperature sensor will change its internal resistance in response to the temperatures it monitors and is connected to the A/C-heater control through sensor ground circuit and a 5-volt reference signal circuit. As the temperature of the A/C evaporator decreases, the internal resistance of the evaporator temperature sensor decreases.

The A/C-heater control uses the resistance reading as an indication that conditions are correct to broadcast an A/C request message on the controller area network (CAN) B bus, where it is read by the front control module (FCM). The FCM then requests the powertrain control module (PCM) to cycle the A/C compressor clutch as necessary over the CAN C bus.

The evaporator temperature sensor is diagnosed using a scan tool.

The evaporator temperature sensor cannot be adjusted or repaired and must be replaced if found inoperative or damaged.