Turning the ac/heater control nob will not move the air to defrost or floor. It only comes out the vents. Why?
Dec 27, 2010 at 6:03 PM
JACOBANDNICKOLAS
✓Experienced Mechanic
110,244 POSTS
It sounds like you have a vacuum leak under the dash. The airflow vents are actuated by vacuum. If there is a leak, it won't shift positions. Check under the dash and the supply hose from the intake. IF you are lucky, you may hear a hissing sound from the leak with the engine running.