Sunload Sensor
WARNING: This page is about a different car, the 2007 Nissan Maxima. However, it is still accessible from the selected car via links, so may be relevant.
The sunload sensor is located on the passenger side defroster grille. It detects sunload entering through windshield by means of a photo diode. The sensor converts the sunload into a current value which is then input into the unified meter and A/C amp.