the dash vents next to the radio open when the car is hot and accelerating, sounds like a vacuum leak, but id prefer if someone had experieced it b4. i have my entire interior apart right no.w. the AC will turn on also if the selector is oncold. btw, 87 z tpi

 

The check valve near the plenum may be defective - its vacuum source is a hose barb fitting at the passenger side rear of the plenum. It isolates the plenum vacuum source from the cruise reservoir, cruise servo, and the HVAC servo vacuum lines.

Tim

 

Check your vacuum reservoir canister, I believe that somone told me that HVAC system defaul position is vent (no vacuum at the manifold), so when you accelerate wide open throttle, there is a major vacuum drop at the manifold, therefore engaging you vents.
afterall HVAC are vacuum conrolled.

Just a suggestion

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'89 Formula 305 TPI T-5
Check out my car HERE!

[This message has been edited by '89Formula305TPI (edited September 27, 2000).]