Ambient Temperature Sensor / Switch HVAC: Description and Operation

Ambient Temperature Sensor - Typical:

Ambient air temperature is monitored by the Compass Temperature Mirror through a PCI data bus message from the NGC engine controller. The ambient temperature sensor is the source for the NGC engine controller. The sensor is a variable resistor mounted in front the radiator, behind the grille, near the left lower side of the radiator support assembly.

For complete circuit diagrams, refer to the appropriate wiring information. The ambient temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

The ambient temperature sensor is a variable resistor that operates on a five-volt reference signal sent to it by the NGC engine controller. The resistance in the sensor changes as temperature changes, changing the temperature sensor signal circuit voltage to the NGC engine controller. Based upon the resistance in the sensor, the mirror senses a specific voltage on the temperature sensor signal circuit, which it is programmed to correspond to a specific temperature.