Ambient Temperature Sensor / Switch HVAC: Description and Operation
AMBIENT TEMPERATURE SENSORDESCRIPTION
Ambient Temperature Sensor:
The ambient air temperature sensor is a variable resistor that monitors the air temperature outside of the vehicle. The ambient air temperature sensor is mounted on the inside of front bumper beam and its data is used by the heating-A/C system to maintain optimum cabin temperature levels.
OPERATION
The ambient air temperature sensor is a variable resistor that operates on a ground circuit and a 5-volt reference signal circuit sent by the powertrain control module (PCM) through a two-wire lead and connector of the vehicle wire harness.The ambient air temperature sensor changes its internal resistance in response to changes in the outside air temperature, which either increases or decreases the reference signal voltage read by the PCM. The PCM sends the body control module (BCM) and when equipped, the ATC A/C-heater control, a specific signal which corresponds to a specific temperature over the PCI bus.
The ambient temperature sensor is diagnosed using the DRBIII(R) scan tool.
The ambient air temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.