One-Way Vacuum Valve

[Neelskit]

I have a 1994 Astro EXT TBI. Does anyone know if there is a one-way vac valve that prevents vac loss during acceleration? I'm having an HVAC issue that only presents itself while the vehicle is accelerating. Thanks!

[brcidd]

You have a vacuum leak- check black plastic line that runs from vacuum reservoir (ball) under HVAC module- to intake manifold at rear of engine- it is most likely cracked or burnt- and sucking air........

[old_master]

Somewhere in that vacuum line, usually close to the vacuum reservoir, there is a vacuum check valve. There are 3 lines that attach to it. If it's faulty, most parts stores have them.

[Neelskit]

Thanks! Will do some checking.