For some time now the climate controls have been acting screwy. When I select windshield defrost the air comes out of the vents below the windshield. If I select vent or heater the air still comes out of the vents for the windshield defroster. When it is selected in one of those three settings I can hear a vacuum leak at the controls. If I select max A/C or A/C it usually works fine, bi-level is questionable. I have already replaced the module on the back of the controls that all of the vacuum hoses plug into but I still can hear the vacuum leak and the controls still don't work correctly.
I'm now thinking that maybe one of the vacuum switches that open/close the vent doors may be stuck open or closed, and that's why air will only come out at certain vents. Does that sound like it may be the case? How hard is it to get to those switches to replace them? I don't think it is any of the vacuum tubes or the plug that they fit into as I have looked them over and they seem fine.

 

Dana,

Search the archives for a thread related to this. I had a lng oration on the possible repair for your problema a month or two ago.

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Later,
Vader
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"Make Me Bad"
Adobe Acrobat Reader 4.0

 

Thanks for the tip, but... I hate to be a pest but I searched for anything that you replied to and the only thing I found that was related was this thread:

https://www.thirdgen.org/messgboard/...ML/001071.html

It talks about rebuilding the air/heat plenum and you talked about cleaning out all of the mold and junk. Unless the thread is beyond the archives, I couldn't find it. So, I hate to be a helpless schmuck but is there anyway you could either point me to the correct thread or summarize what you said in it? Thanks in advance, I appreciate the help.

 

I've had the exact same problem. Replaced the vauum switch and it worked good for two days then quit again. When the weather got cold it started working OK! I suspect that there is tension on the switch or one of the vacuun lines that is tugging on the vacuum selector and twisting it out of shape a little. Mine had a stereo install before I got it and that might have rearranged things.

 

OK - I'm gonna try this again - I keep getting kicked off - ISP or something. If you already replaced that vacuum switch, the problem you are having lies with that rubbery manifold that all the tubes are connected to on the back of that switch. It might look like it's good but it's not holding a seal. My car did the exact same thing. 2 ways to fix it: hard way is to remove most of the dash to replace that harness (one piece), or the easy way is to modify that manifold. You will have to note the position of each tube on the back of the switch cuz you won't have a manofold when you put it back together. What you have to do is cut the manifold surface so that you have all the tubes separated. Trim off all the excess manifold rubber so you have "neat" tubes, but do not cut the colored tubes themselves. re-attach the tubes to the correct positions on the back of that vacuum switch. They will hold nice and snug by themselves, but I used the real small zippy-ties on each tube on mine. The system will seal and work like a champ. I took my stereo out for easier access, too.

 

Thanks thunderstick, I'll give it a try. That sounds like it could be the problem. One question though, do you really need to cut the manifold apart? Or could you just put the zip ties around the rubber tube part with the manifold intact? I can't remember exactly what the manifold looks like so I don't know if it would be possible. Anyways, I'll look into it, maybe this weekend I will have a functioning air/heat selector.

 

Dana - the manifold is the rubbery thing that all the tubes connect to, which slides on to the back of that vacuum switch. I suppose you could try to zippy-tie each one with the manifold still intact, and you could probably even try to use RTV, as well. What happens is that the manifold part gets kinda sloppy and won't allow the seal to remain intact. The only pain in the butt is that you may end up having to take it out a couple of times... I just did the manifold thing, by separating the tubes and it worked like a champ. If worse ever comes to worse, the vacuum tube harness is only like $5, BUT, you gotta remove alot of dashboard to get to everything it connects to... Good luck - let me know how it goes.

KAM

 

l had the same problem in my car. My solution is even easier. Pull the manifold off. Wipe it off well. l just used a rag. Then reassemble. Mine worked fine after that, and its been over a year now. What happened was the junk between the manifold and the plastic wasnt allowing a good seal. Now l have no problems w/ the climate controls.

Clayton

 

Well, I tried your fix thunderstick this weekend and it still has a vacuum leak. I didn't cut the manifold totally apart, just enough to get a zip tie around each tube. What I think I may try next is getting a new vacuum tube/manifold harness if they are as cheap as you say and just splice in the new manifold onto the old harness. I'll experiment before I actually do it but I think that will work. I think I can find some plastic tubing that will fit snug over the vacuum tubes to connect the two ends that I will cut and use a good glue that will hold it together and make a good seal. Then maybe some shrink wrap tubing over it all. We'll see, at the very least I'm getting real good at taking my console apart!

 

If you're gonna splice that manifold piece anyways, I'd try the individual tube thing, cuz if you're gonna do what I think you are, you're pretty much going to have it apart anyways. Just a suggestion... When you do remove that "manifold" next time, plug the hole over the purple tube (vacuum source) and make sure you don't hear a leak then. It doesn't even feel like there'll be much vacuum, but it's pulling about 21". If you don't hear a leak, your problem is still probably in that manifold. You did replace that switch, right? Yea, I got pretty good at pulling that stuff out, too. I ended up taking the mount brackets for the a/c head and the stereo out and cleaned them up and repainted them because they were kinda rusty looking. Good luck - I hope you get it.

KAM

 

I called the dealer and the manifold/vacuum tube harness is $20. Cheap enough for me to cut up and experiment on. About 2-1/2 years ago my stereo got stolen and the console was smashed up in the process. I had to replace the entire temp selector along with the entire console. I don't remember exactly when I started having the vacuum leak but I do know it was after that incedent. About 4 months ago I replaced the part on back of the temp selector unit that the rubber manifold plugs onto thinking that maybe it was that. It didn't make a difference so I'm sure it is the manifold. I'll consider the individual tube idea, at least it will be easier to work on (i.e. seperate into individual tubes) when it's not in the car. Thanks again for your help, I'll post when/if I fix it.

 

$20? That's a rip deal... I swear to God, I only paid about $5 for mine. Let me know how things go...

KAM

 

Ah crap! You're right about the price, I got ripped. I checked with a few other sources and the harness is only like $5. Oh well. There's a Chevy dealer warehouse just down the road from my work so I usually just go there, but I probably not anymore since they are so expensive.

 

I experienced this problem for many months. A few days ago when I was at my GM dealership, I happened to mention the problem to the parts man. He told me to remove the vac harness on the rear of the AC/Heater control and swab the black plastic tubes (the ones that insert into the vac harness) with Vaseline. I did. Much to my amazement, the fix worked--all for $1.11 for the Vaseline and thirty minutes for my time.

JamesC

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[This message has been edited by JamesC (edited November 15, 2000).]