Astro Ventilation

[68Zproject]

I was reading a site that has brochures for older cars and was reading on the 68 Camaro Astro Ventilation.  One states that " Sport coupe models feature special pressure relief  valves to keep air flow constant".  What is that?

[JohnZ]

Astro Ventilation (also called "High-Level Ventilation") provided for cabin ventilation without vent windows, which were eliminated after the 1967 model year. Air inlets at each end of the dash (connected to the rear wall of the plenum panel below the wiper grilles) admitted outside air (Assembly Manual, UPC 1, sheet M1) and included flow control knobs. Air exited the cabin through the plastic grilles in the upper door opening area of the rear quarter panels, which have rubber flappers so air can only flow OUT, and not IN.

[68Zproject]

What's the "pressure relief valves"?  The knobs to control the flapper?

[Sauron327]

What's the "pressure relief valves"?  The knobs to control the flapper?

There's a rubber one way flapper inside the plastic door jamb vent/louver.  Sometimes originals are disintegrated.

[68Zproject]

Gotcha.  I hear a bell ringing.  Had the flu don't know if that's why the uptake is so slow.  Creative ad copy I guess.