Like in the title the floor vents stay on when I have the vent controls in the off position. The speed of the air coming out of the floor vents seems to increase with vehicle speed. However, the floor vents work normally in all positions except for OFF. I have looked at shoebox's diagram here and am thinking that I have a vacuum leak to the yellow tube.

Is there an easy way to test this? Could there be anything other than just a vacuum leak? I would think that the compressor would be turned off when the vent controls is in the OFF position anyway so this isn't really making sense. Someone please help.

 

if it was a vacuum leak it should go to the drfrost position. does it switch nomaly by the mode selctor ir does it just always stay there?

 

You will always get a little air through the floor vent in the off position. It keeps the air in the cabin from stagnating.

 

Yeah I used to have that problem. Under load I would lose the instrument panel vents, but I fixed that one. Everything switches normally with the mode selector. When I select something that doesn't use the floor vents, they turn off. The floor vents only stay on when I have the mode selector in OFF.

 

hmm... you could be right shoebox. The strange thing is, at idle I can't even tell if there's any air coming out, but at about 45mph and up the vent feels like its on max. Its really irritating because it starts to get your feet pretty hot.

 

I have owned about 11 different GM cars since I was 16 and all of them did this. There isn't anything wrong with your car, it's normal for it to do that. If you change the temp setting it wil blow hot or cool air through the floor.