GM Service Manual Online
For 1990-2009 cars only

The inside air temperature sensor is a temperature-sensitive resistor similar to the outside temperature sensor. As cabin air temperature increases, resistance decreases. As cabin air temperature decreases, resistance increases.

A fan located in the in-vehicle air temperature sensor housing continually draws passenger compartment air over the sensor. This condition increases the accuracy of the temperature reading.

The heater and A/C control module monitors the vehicle temperature signals and uses this information in order to help determine command signals.

Upper and Lower Outlet Temperature Sensors

The heater and A/C temperature sensors are used in order to monitor discharge temperatures from the heater and A/C outlets. These sensors are located in the heater and the A/C ducts. The heater and A/C control module monitors the discharge temperature sensors and uses this information in order to help determine command signals.