Amphenol Advanced Sensors OAT Sensor measures the temperature outside a vehicle's passenger compartment. This outdoor air temperature sensor is typically mounted inside or near the front bumper or in the side mirror. The sensor relays the outside air temperature to the controller of the automatic heating, ventilation, and air-conditioning (HVAC) system. The HVAC controller uses this temperature to help control the vehicle's interior temperature. Amphenol Advanced Sensors OAT Sensor also provides the vehicle occupants with temperature readings from outside the car. This information is beneficial when driving in near-freezing or freezing conditions.