My HVAC door vacuum selector switch is leaking, causing the system to go into defrost mode. I took it apart and still looks great with adequate lubrication. Apparently, there is something I can't see or it has shrank/distorted/hardened to the point of letting air past the seals.

Does anybody know if these vacuum switches are still available? I ordered one from NAPA a few years ago, but they can't get it anymore. I found a post from last summer from someone having the same problem in finding one. I was hoping a manufacturer might step in to start producing these again.

 

UPDATE:

I found several places that initially said they carry the switch until I put in an order. Then it would say it is unavailable.

But, I found two places, gotpartsnow.com and theautopartsshop.com. theautopartsshop.com order didn't seem to go through all the way when I used the PayPal option, so that one is up in the air. I got an order confirmation from theautopartsshop.com, but I guess I'll see what happens Monday. I'm expecting a reject letter from them, (And refund, I hope!)

 

So, besides trying to order a new one, has anybody tried another fix for this? I can envision a series of micro switches operating off the control lever that operate vacuum solenoid valves but that would be complicated.

I found one, maybe two other GM switches, but they were physically different and probably operationally different too. I don't know if they could be modified to work.

 

Is it plastic? If so, fixing it is usually futility.

I wouldn't try one from a different application. I bet they are all slightly different in how they function. Or at least in terms of which vacuum line goes where. I say this based on the fact that different GM cars have different "default" vent positions. The 3rd gen F-body it's the defrost. On many it's the floor vents. On some it's the dash vents. Not worth it for the headache it could cause, in my opinion.

 

have you verified thats the part thats failing and not a cracked/disconnected vaccuum line?

 

Yep, went through it all. The vacuum canister was leaking too, cracked at the end. The hard plastic line from the canister to the switch holds a vacuum. I can also hear the leak at the switch when I apply a vacuum directly to the inlet port with the outlet ports plugged.

 

best bet is going to be a junk yard. noone makes them anymore. call hawks or third gen ranch.

 

Yup, LOTS of cars use the same, or similar enough, valve. At worst you can always just get the vacuum line plug that goes with the switch out of whatever car you get the valve from, just leave a few inches of lines on it, and splice it to your existing lines.

 

Mine just went again aswell and I got mine from napa in august

 

Yep, as is usually the case, the original parts last faaaaarrrrr longer than the non-GM replacement parts.

All of my possible sources were out of stock. So I ordered the other switch. I still have to see if it can be made to work in my application. I did notice that the new one is a little bit larger in diameter, has only one mounting ear and that ear is clocked about 30 degrees from the vacuum connector locating pins. See pics below. New one is on the right.

I'll post my results.