I am just new to this forum and I'm looking for advice on a heating/ air condioner problem with my 80 Vette.

Welcome to C3VR, first!!

Definitely sounds like a vacuum problem. You may not be getting any vac. to the selector at all, or the selector may be dried out, unplugged, or otherwise damaged.
Try taking the selector/switch assembly out, and looking to see if the vacuum plug is connected, first. This will be a plug with several flexible, colored vacuum hoses on it. If it is not plugged in, then that is most likely the problem. If it is plugged in, unplug it, and start the car. You should be able to feel vacuum on at least one of the hose ends. You may need to use a vac. gauge, but usually, you can feel it. If there is vacuum, then the selector switch has probably dried out inside, and needs to be replaced, or some of the hoses that go to the vac. servos are off.
If there is no vac. at any of the ends, then you will need to start looking under the hood for a small vac. line that is not connected.
This should give you something to start with, anyway...good luck!! See what you find, and let us know.

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Joel Adams
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Joel,

Ian, you may need to replace the vacuum canister on the main air box. I had mine apart a few years ago and can't really remember. But the canister shifts the air flow by swigging a large flap inside the air box. And sorry to say its a B*$%ch to get to. Also check the heater/control located in your console. Thanks

The vac. servo by the pass side kick panel is for the "Max A/C" door. It should be open in any position except "Max".

I'm not familiar enough with the guts of an '80 dash, but I would suspect you will need to at least remove the glove box, to get look back in there. The earlier cars, you can remove the pass side dash panel, and get a decent look, even tho you may not be able to get your hands on the parts!
It does sound like one of the doors is stuck, or has a bad servo, as Guy says...

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

joel, i need to ask a question.  my a/c doesn't work in my 78.  i would like

Depends on how far you want to go with it! If you just want to remove the compressor, condenser, and the lines, then that's all you need to do. This will not effect the operation of the heat/defrog.

If you want to totally remove all aspects of the A/C system, then you're talking about a major undertaking, involving replacing the heater core/plenum, console controls, and vent outlets, with non-A/C car parts. Lot of trouble, imo...

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

  oh no,  i just wanted to take the stuff out from under the hood, not everything else.   how do i go about knowing which stuff to take out, undo, etc

Just start rippin crap out!!

You can remove the compressor, and the brackets(at least some of them). The hard and rubber lines from the comp. to the condenser. The condenser itself(in front of the rad). Plug the hoses/lines that are left on the car(going inside the cabin), and yer done!


btw...we may need to take this to a new thread, so this one stays focused on the original topic. Adams' Apple2007-10-12 20:11:24

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

thanks.  sorry for buttin' in on the wrong forum

It's kewl.
Just didn't wanna get too far off on something else.

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Ian 80, I recommend that you remove the entire heat/air system and install a totally new one made by Hot Rod Air.  Their system always works, it is reliable and all of your problems will be solved, including most of your vacuum problems.  See hotrodair.com.  Believe me, you will be chasing a/c and heat problems for the rest of the time you own the car unless you change the entire system.  They were never reliable, even when new.

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I'll look them up.  Thanks

Kind of expensive.. I was hoping I would get some advice on troubleshooting the stock system.

Hot Rod Air issues.  Thermostat switch which they provided failed.  Called HRA in early October for a new one, which should be under warranty, they said they would send it immediately.  Every week for the last month I have called them for status which always has been that their supplier has sent them, they will arrive any day and HRA will send it as soon as it arrives.  Even talked to the owner two days ago who indicated that the switch should arrive yesterday and would be shipped.  Guess what, the switch did not arrive.  Bottom line-good system until something fails and then their product support is lacking.

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C3VR Life Member #4
NCM Life Member #994
Vietnam Helicopter Pilots Association Life Member