no matter where i turn the climate control knob to i get air out of all vents and even if i turn it off air still comes out. what gives?

Sounds like a bad mode valve actuator. It's a small electric motor that moves the door that redirects air to the different positions. The older Grand PRixs were vaccum operated, but your's is electric. AC-Delco part # is 15-72985 (GM#10349563).

no matter where i turn the climate control knob to i get air out of all vents and even if i turn it off air still comes out. what gives?

unfortunately with anything elctrical work is always the first thing to go. my GUESS would be it has something to do with the main unit of the climate control center. something in theres not telling what vents to open and what vents to close to allow air only to go through certain vents. im not sure how but maybe just try swapping out yours with your buddies and see if the problem goes away if it does it was the main unit that went bad otherwise your in for some diagnosing lol