heater duct control

[1st TA]

My boy has a 94 Z. When he is on the gas a little heavier the air coming out of the ducts will change outlets. Then when he backs out of it it changes back to where it was. What should I be looking for?:brick:

[SloLt1Camaro]

A new car?

[psychoticLS1]

the a/c vent controls are vaccum operated. I believe there is a check valve inline to keep the changing manifold pressure from affecting the vents until you actually change the switch. Also check your vaccum lines and make sure you don't have cracked a line or tore a boot

[1st TA]

If I start the car to get the vac. going then unplug the hose to the check valve should the check maintane the vac. if its good?