Ambient Air Temperature (AAT) Sensor
WARNING: This page is about a different car, the 2017 Lincoln Navigator and 2017 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
The AAT sensor is an input to the PCM. If the outside air temperature is below approximately 0 °C (32 °F), the PCM does not allow the A/C compressor clutch to engage.