98 Sonoma Hvac

Everything seems to work correctly except the position switch. Seems all the air comes out the dash vents no matter what position the switch is in. There is no foot vent or defroster. So is it the switch or is there a vacuum problem?

98 Sonoma
4 Cylinder Automatic
Extended cab

it could be a problem with the switch, or a vacuum leak, but it could also be that the doors that control the flow of air are stuck in one position. you should check for vacuum pressure at the switch, if there is none then you know its a vacuum leak. when you turn the switch you should hear a hissing sound for a couple seconds as the vacuum takes effect. (if you need help accessing the back of the switch just ask.) if you find there is vacuum at the switch then the switch is bad, if not then you have to find your leak and fix that

Thank you Spitfire, I read other articles on automotive forum and decided to check it out. I disassembled the dash molding looked at the hvac switches and decided everything was working properly. Then I decided to go in the engine compartment and I looked around and sure enough I realized I had a vacuum hose disintegrating. So I took somebodies advice and cut the hose and went down to the auto parts store got some new hose and put it on and now it works great.