I want this left in general topics because of not sure what exactly is the problem, and I want ideas, experiences, and hopefully a specific diagnosis.

Not sure if this entails, a problem that has happened a lot....interior, console, engine part under the hood, or whatever...which is why in general


1996 LT1...pretty beefy with racing rotating parts (all go and no show per se')

All of a sudden the car runs bad...and the A/C vents have a problem switching from defroster to vent....son was driving, struggling to get vents to blow.

OK, that would 90% indicate a vacuum leak.

But, it only did it during closed loop.....hmmmm...maybe just coincidence it happened at that time.

So....runs bad all of a sudden, vents, dont work correct...whats the chance that its the A/C control panel or vacuum door?

See, I want it to be a burnt vacuum line under the hood right there in the wide open....just splice it, tie it off and no more problems.....thats what I want it to be.

But....


It may entail ripping apart dash and console to replace vacuum door or control panel....maybe even a vacuum line broken under the dash/console/ control panel.


Now, the other question.....are there part still available?
new A/C control parts, or vacuum doors available?



Oh....and FYI...I loaned it to a friend when his rear diff exploded, then my son lent him his truck so my friend could go chase down a diff....my don was driving when this all happened.
Dont give me grief about loaning my car....its just a car, good friends and family are harder to come by and are more important than a car.

I am thinking maybe one of their big foots went up in the back of the console and knocked off a vacuum line.




Thanks,
Jim



Strats-N-Vettes2009-08-09 11:59:39

Runs bad, AND the HVAC doors aren't working? Absolutely sounds like a vacuum issue.
 It would have to be a pretty good sized hose for it to effect the engine that much. Perhaps a vacuum line simply blew off under the hood, but it's entirely possible one of the plastic lines did get melted. Can't see anyone's big feet knocking anything loose under the dash of a C4, but if so, it would pretty much have to be right there at the center dash/firewall area. That's about the only place under the dash that you can even see, much less touch! I think I'd be lookin under the hood. You might even be able to hear it hissing, depending on the exhuast.
hth

[QUOTE=Adams' Apple]Runs bad, AND the HVAC doors aren't working? Absolutely sounds like a vacuum issue.
 It would have to be a pretty good sized hose for it to effect the engine that much. Perhaps a vacuum line simply blew off under the hood, but it's entirely possible one of the plastic lines did get melted. Can't see anyone's big feet knocking anything loose under the dash of a C4, but if so, it would pretty much have to be right there at the center dash/firewall area. That's about the only place under the dash that you can even see, much less touch! I think I'd be lookin under the hood. You might even be able to hear it hissing, depending on the exhuast.
hth
[/QUOTE]

on my 90 there is a vacuum hose that goes from the throttle body to the vent on the valve cover. line was patched by PO and drove me crazy as the hose lies under the plastic channel that holds the injector wiring. found it by accident and solved part of my problem. just something you might want to check if your hose runs the same way.

Thanks Eddie...will check many things when I get to the car.



Jim