What is the Ambient Temperature Sensor (Switch)?
Modern automotive HVAC systems have advanced by leaps and bounds over those used just a few years ago. Nowadays, many high and even mid-range cars offer automatic climate control. This function basically lets you to “set it and forget it,” enabling the car’s computer to control the heating and cooling based on your preferred interior temperature. In order to do this, the computer needs information about not only the temperature inside the car, but also the ambient temperature outside the car.
The ambient temperature sensor (switch) is situated either behind the front grille or in the front bumper. Its only job is to monitor air temperature (which it does through increasing/decreasing resistance in response to temperature fluctuations). This information is transmitted to the car’s computer, which then adjusts the climate control to meet your specifications.
If the ambient temperature sensor is damaged or fails, the car’s computer will not be able to automatically control the HVAC system, and the heater and air conditioner will only work in manual mode.
Facts to Note:
Because of its location, the ambient temperature sensor can be easily damaged in even minor front-end collisions.
Sensor failure is common even without an accident.
How to Note:
The ambient temperature sensor switch is confirmed to see if it needs to be changed
The faulty ambient temperature sensor switch is removed
The new ambient temperature sensor switch is fixed
The ambient temperature sensor switch is tested for operation
The vehicle is tested to ensure proper operation of the ambient temperature sensor switch
Without the information provided by the ambient temperature sensor, your car’s computer does not have sufficient data to control the interior temperature, and will revert to manual HVAC control. You’ll still be able to use your air conditioner and heater, but only in manual mode, not in auto. If you suspect a problem with the ambient temperature sensor, have it analyzed by one of your expert mechanics and replaced if necessary.
Common signs indicating you may need to change the Ambient Temperature Sensor (Switch):
HVAC auto mode will not work
HVAC auto mode produces delivers inconsistent/incorrect operation
HVAC will only work in manual mode
Outside temperatures may display incorrectly
Importance of this service:
Having automatic climate control is definitely a convenience, but not critical to the operation of your vehicle. The heater will still operate to clear the windows and provide heating and cooling on manual mode. If the ambient temperature sensor is defective, have it changed.