Dash vent won't shut up

[Djacob174]

I have a 1999 Pontiac Grand Am with the 2.4l DOHC. While I was driving today I turned my air on and I heard a weird noise coming from the single passenger vent. It's like a whining noise. Also, when I change the dial to switch which vents it blows out of, it won't stop blowing out of the dash vents. My heat and AC work fine. What is this weird noise and why won't my dash vents stop blowing air?

 

[5speed406]

Sounds like the actuator motor that opens/closes doors in the air box has gone bad. Mine does the same, the noise has stopped now but air comes out of upper and lower vents all the time regardless of switch position.