Circuit Description
WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.
The ambient air temperature sensor allows the HVAC control module to monitor the temperature of the air surrounding the front of the vehicle. The module applies 5 volts to internal input resistors that are connected to the signal circuit of the ambient air temperature sensor. The module provides ground to the ambient air temperature sensor through the low reference circuit. The HVAC control module monitors the voltage drop across the ambient air temperature sensor and uses the input for automatic control calculations. When the air temperature is cold, the resistance of the sensor is high and the voltage signal is high. When the air temperature is hot, the resistance of the sensor is low and the voltage signal is low.