Theory Of Operation

The HVAC Module uses a variety of sensors to adjust HVAC operation to obtain optimal performance. These sensors are continuously monitored by the HVAC Module to assure that they are in range. An active DTC indicates that a sensor is out of range. A stored DTC indicates that the sensor was out of range but is currently within range.

The Cabin Temperature Sensor (also known as the In Car Temperature Sensor) uses a temperature thermistor which changes in its resistive value with differences in air temperature of the interior cabin. Air is drawn from the passenger compartment by an aspirator (small fan driven by a 12-volt electric motor) which circulates air over the temperature thermistor. The HVAC Module receives the resistance value over a two wire circuit that is used to calculate the temperature and make any adjustments to maintain the optimum passenger compartment comfort. The Cabin Temperature Sensor cannot be adjusted or repaired and must be replaced if inoperative or damaged.