Sunload sensor
WARNING: This page is about a different car, the 2015 Lincoln MKT. However, it is still accessible from the selected car via links, so may be relevant.
The sunload sensor uses two photo diode cells inside of it to measure the intensity of the light that enters into the passenger cabin of the vehicle. Based on this information, the HVAC control module increases blower speed and adjusts the temperature settings to lower the vehicle's interior temperature.