Well, I'm back after quite a sabbatical. My '94 Z has been cruising along just fine serving as my daily driver, with virtually no problems. About a year ago I noticed that when I had the engine under a high load, low vacuum condition (like climbing up a hill in 6th gear), the vent controls would re-route the air away from the in-dash vents down to the floor vents. I assumed that this was probably a check valve that had died, and was no big deal (gotta get me one of those round to-its ).

Last week the air control stopped working completely, and the air is now directed through the floor vents 100% of the time. There's no hissing sounds, and the manifold pressure is down around 8" Hg at idle, so I don't think there's a vacuum leak (at least that the engine's seeing).

I went through my shop manual this morning, but didn't find any kind of diagnostic for the vacuum system.

Can someone help me out here, either directing me to the right part of my shop manual or give me some tips before I start gutting my dash?

TIA, and have a good one,
Mike

 

I had that exact same problem in my old '93 Lumina. The cause was a corroded vacuum hose (battery leakage). Now, I don't know how the Camaro is set up (I've only had it for a few months, and haven't really been under the hood very much), but it's something you might want to check if you haven't already.

 

On my 95 there's a vacuum line that comes off the passanger side of the intake manifold for the vent control system. It leads into the interior through the wiring harness located just in front of the computer. It also ties into a vacuum reservoir located just below the passanger side headlights.

 

Thanks! I'll get under there and start checking things out tonight. Do you think I'd be seeing a higher manifold pressure at idle if it was leaking at the intake manifold?

Thanks again, and have a good one,
Mike

 

A vacuum leak will definitely cause your intake manifold pressure to increase. Easiest way to check is to remove the vacuum lines one at a time from the intake manifold and plug them up (at the manifold) and watch for an increase in vacuum on a vacuum gauge (while your engine is idling).

 

Finally, an update. It took forever because my family car ('96 Crown Vic, don't say it! ) decided that it's heater coil would start leaking, and I had to take the entire dash OFF to get to the stupid thing. Two entire weeks of spare time to fix that stupid thing!

Anyway, I finally found the vacuum line you were talking about: I just didn't realize that the line was up by the passenger side hood hinge. I kept looking at the intake manifold area and never got it traced correctly until I came at it from the interior. Sure enough, it had disconnected itself right there where you said.

So, thanks for the help, thought you might want to know the final outcome.

Have a good one,
Mike