Upper & Lower Air Temperature Sensors
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
Both Upper and Lower Air Temperature Sensors provide the IPM with the temperature of the air exiting the A/C ducts located at both right and left A/C ducts. A reference signal is sent from the IPM to both the Left and Right Air Temperature Sensors. A thermistor inside the sensor varies the voltage. Remaining voltage is sent back to the IPM, providing input from the sensor.