Ambient Temp Sensor: Operation
WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
The ambient temperature sensor is a variable resistor that operates on a five-volt reference signal sent to it by the A/C-heater control. The resistance in the sensor changes as temperature changes, changing the temperature sensor signal circuit voltage to the A/C-heater control. Based upon the resistance in the sensor, the A/C-heater control senses a specific voltage on the temperature sensor signal circuit, which it is programmed to correspond to a specific temperature.