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Air flow control

J

JLank

New member
Hello group,

This is my first question, so I hope I make it clear enough to understand. I'm having an issue with the air flow for heat/air. The blow motor is running fine, but apparently there is something that controls where the air gets diverted to - like upper vents, floor vents, upper vents + floor vents, defrost, etc. When I switch between them, it seems it takes several seconds, if not minutes (if it ever switches at all) for whatever it is behind the dash to fully change so the air gets diverted where it needs to go.

For example, now that's it's prime-time summer time, I'm using my A/C a lot. When I switch to upper (dash) vents only, it's like the air flow coming from the vents is very weak. A couple days ago I drove into town and about 1/2-way there I heard something "slap" under the dash, like a diverter door or something finally moving into the position where it needed to be, and then all of a sudden......WHOOSH! The volume of air was strong and what it should be.

What controls this switching mechanism, and what should I be looking at/to for determining why the mechanism isn't as responsive as it should be when changing the output location.

Thanks!
 


Hey jlank I was having the same issue last year but for some reason it seamed to start working one day and I haven't had a problem since. Also iirc the damper is controlled with a vaccum. I could be wrong
 


not a blend door. those make it hot on one side.

your vents are vacuum powered. off the engine is a line to the fire wall, it then leads down the inner fender under the fuse box and into the cars harness. if you changed your battery or removed it, check the line there, it may have snapped. or it can break from the engine any where to the cars harness.

if the vac line under the hood looks ok, then theres a box under the dash the same line leads to, it goes bad.
 
Thanks Scottydoggs - where does the vacuum line tie into on the engine? If I can locate that I might be able to trace it back. Thanks!
 
na engine, back of the upper intake, next to the brake booster hose.


sc atop the sc next to the brake booster hose.

both mount to the fire wal then down the pass side fender under the fuse box and into the cars wire harness.

you can see it on this pic.

PA150055.jpg
 
It looks like you have the supercharged engine? Mine is a GT with the 3800. Is the hose the one I have circled?

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thats the booster hose, follow the same hose to the back/ side of the intake, next to it is the small line that you see in my pic near the alt to the fire wall. it leads under the fuel lines to the manifold on top the blower there.
 


Ok, I'm just getting back around to this. I believe I have found the hose you're referring to. I tried to add attachments but they kept failing. Assuming I have the correct hose - how do I go about troubleshooting?

Thanks,
James
 
go to a parts store, buy a foot of vac line, then cut two inches off it, cut the old dried up hose end off, replace with the new vac line you just cut.

most stores will give you scraps to test fit with. if you get to use scraps, ask them how much for this 2 inch piece. after you find the right size. i bet the guy tells you to keep it lol
 
That is what I believe to be the line. It doesn't appear to be blocked, but how will cutting 2" off the end help? Do I need to connect a vacuum tester to the line?
 
if that hose, yes thats it, the little one, is coming off on its own, you take the old rubber off and replace it, then push it back on.
 


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