Chevrolet Repair: AC Vents, vacuum tank, check valve

Question
On my 1999 Monte Carlo Z34 my AC vents start blowing on my feet as I accelerate. When I let up on the gas they go back to normal.  

Answer
Hi Mark, You need to check the vacuum check valve for the hvac system that comes off the intake manifold. This valve stops vacuum from going back to the engine. There also might be a leak in the vacuum tank or lines. I would first check the check valve these are more common.


Hope This Helps

Mark