Q: When you turn on the fan for your heat or ac the upper vents (dash board)do not on 2002 Chevrolet Astro

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
blow out.The box under the dash by the passanger gets loud with the sound of forced air.
(1) Answer
You probably have a broken vacuum line to the control head. Vacuum is used to control the vent/defrost damper, and if the line is off it won't move. This could be under the hood, or the connector could be broken on the switch itself.
Didn't find what you were looking for?