Air vents don't work

Sounds like you've lost vacuum to the climate control system. Look for a broken or disconnected vacuum hose that goes from the engine through the firewall. On my 2000 Grand Prix it's a small vacuum hose that runs along the passenger's side wheel well next to the hose for the windshield washer. Hope that helps! Jim

I agree but it could also be at the rear of the dash controller where the vac hose connects.

And I believe there's an actuator in there somewhere that actually opens and closes the doors in the venting to direct the air to the various parts of the car. That failed in my Bonneville from that era once upon a time. Was a fairly big job to get to and replace as I recall.