Function & Override Buttons: Def
WARNING: This page is about a different car, the 1999 Lincoln Navigator and 1999 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
Pressing DEF button will show defrost icon and the selected temperature in the display window. Most air will be directed to defrost vents, with a small amount going to floor ducts and side window demisters.