I have a vacuum leak on my HVAC system, and was narrowing it down today.

The line from the manifold to the check valve is ok, so is the one from the checkvalve to the resorvoir. Now the one from the check valve to the car is iffy. It holds vacuum but loses it slowly.

I had put the selector on the inside of the car to OFF, and it loses vaccum slowly, about 20 inches of vacuum 1 pound every 30 sec. If i put it on any A/C related function, like defrost or the a/c postion, it loses it pretty fast, like all vacuum in 30 seconds.'

I am thinking it is the seclector, but if it is the line how do i replace it? It looks like a ***** to remove/replace.

Oh yeah, my car pulls 19 in of vacuum, is that good? It is all stock really, cept for mods in sig.

 

Hmmmmm can't help ya with your problem but notice your from Crossville . Can't seem to place your car ? Been here long ? Have you tried taking it to any of the local shops ? Give me a shout somtime .......
Billy C

 

You will have to isolate the line from the check valve to the mode control and check it for leaks. There is a multiple connection point behind the glovebox and then, the hose from there to the mode control.

 

hey shoebox.... i found this old thread talking about the mode selector and itsmultiple hose connector things when you switch it. does that mean i may have to check all those connections?
http://web.camaross.com/forums/showt...ghlight=vacuum
I guess i pull out the bezel around the radio and then.....? What do i do after that? or do i pull down the glovebox? sorry i have never had a vacuum prob ever b4 in my little 18yr old life

wierd thing today it worked fine? I know it is leaking though somewehre.

 

You might want to check to the connection behind the glovebox first. That's your first possible trouble point and probably easier to get to. If needed, you can test toward the mode selector from there. When the mode selector is set to OFF, it should effectively close vacuum off to all other ports and hold vacuum back to the engine.

Ever notice how you can come back to your car hours later (not starting the engine), move the mode selector and it will function (you can hear it hiss when bleeding off the vacuum)? This could not happen if there was a leak somewhere.