Temperature Control Button (328 Series)
WARNING: This page is about a different car, the 1996 BMW M3, 1996 BMW 328is, 1996 BMW 328i, 1996 BMW 318is, and 1996 BMW 318i. However, it is still accessible from the selected car via links, so may be relevant.
Temperature control buttons determine temperature of air entering driver-side or passenger-side compartments. Pressing left side of button will decrease air temperature. Pressing right side of button will increase air temperature. Driver and front passenger can select individual temperature ranges.