No vacuum to HVAC system, stays on defrost

[pagrunt]

Didi you check the male/female vacuum connector that is under the glove box? I had mine break one one the male end & screwed with the vacuum circuits.

 

[Buford T. JuSStice]

If all else fails, I wonder if I'd be able to set up an electric vacuum pump and put it in place of the vacuum reservoir or under the dash somewhere. Just pulling a constant 20inHg. Under the dash I suspect it'd be a noisy little bugger, but under the hood, you'd hardly notice it even exists.

 

[Buford T. JuSStice]

Didi you check the male/female vacuum connector that is under the glove box? I had mine break one one the male end & screwed with the vacuum circuits.

Yes, that's how I checked all the vacuum doors. I went directly to that connector and tested each door individually. The only one I wasn't able to get visual confirmation on was the upper mix door with the Red hose, but I could hear it moving.

 

[TURNA]

disconnect the purple

get 6ish feet a regular black vacuum line or hose

hook it up under the dash out the window under the hood to the port

see if that works

if it does you found the problem for about 5 buxx and 5 minutes of work

 

[Buford T. JuSStice]

disconnect the purple

get 6ish feet a regular black vacuum line or hose

hook it up under the dash out the window under the hood to the port

see if that works

if it does you found the problem for about 5 buxx and 5 minutes of work

Not gonna lie, wanna know what I tried? I tried disconnecting the violent(purple) tube at the vacuum reservoir, and then blowing vape into it to see if I could see a cloud coming out somewhere. Didn't work though, because all that was coming out was a little faint stream of smoke that disappeared instantly lol.

I'll definitely try that though. Diagnosing these vacuum lines is actually not ALL that bad. It's like figuring out an electrical problem, only easier.

 

[rogus]

Maybe these diagrams could help? If all the lines are ok and vacuum signal is good...it may be the selector valve in the head unit disc may not be in good shape or one (or more) of the mode valve actuators' aren't cooperating.

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By any chance are these diagrams good for the 81 Elky as well?

 

[fleming442]

Did you put the vacuum pump on the purple under the hood. Get some vacuum on it, and see what happens.

 

[pagrunt]

By any chance are these diagrams good for the 81 Elky as well?

They are the same for '78-'88.