TrailBlazer20

it blows air out every place exept the vents in front of the dash. need help hot outside thanks

taillight

Check the mode actuator and door.

Richard S

I can't remember if that one has what is known in the GM world as a football under the hood or not, it is basically a vaccum bottle. It is shaped like a football or sometimes like a basketball with one hose on it. I have seen the bottle go bad but most of the time the vaccum hose will come off or is cracked and air will blow through the defroster vents and other places.