I have an 86 El Cam with 305.The a/c works but the cold air comes out under the dash & out the defroster vents.After driving for a long time it will come out a/c vents in dash.but some times you might be dead from the heat before it happens.Luckily it seldome gets hot in E.Central Fl. LOL.Anyone know what the problem is? & how to fix it?

Chris,
Sounds like you have either a vacuam problem or the vacuam actuator on the back side of the heat / a/c controls is failing, being that it works after a while kind of points to the actuator on the switch.

Problems like these are where a shop manual is worth the cost, there can be several reasons but these are the two I would check first.


Mike

You should be able to pick up the vacuum control module/switch/actuator from an AutoZone or PepBoys fairly cheap since GM used this type for many models. It's easy to replace. You don't have to pull out the radio, just the cover and the face screws for the controls.

I had to replace mine twice. About every 6-10 years.

Tip: change the lamp while you're in their too.

http://i1122.photobucket.com/albums/l536/T3RMN8R/siglogo/terminator-ss-1.png

Mine was that way and it was the small actuator (two hoses) on the back left corner of the switch was bad.

Thanks Neil & others.

Neil you were right,I replaced both vacuum switches behind the a/c controls today & now every is working ok.took it for a test drive & it is a lot cooler than ever before.Thanks Neil & others.

I think I need to do that too. Where did you get the switches, and do you have part numbers? I have been chasing the same problem in my 86 Silverado.

In the LMC truck catalog it only shows one vacuum select switch. Can't remember if I saw two when I was in there.

Thanks, Terry

I got these parts thru El Camino Store.Part 07-0672 vac switch $23.99 & part 07-0671 vac switch $27.99.part 07-0671 is avaiable at autozone for about $4 less but you have to order it but you will save on shipping costs.they don't have the other part so I ordered them both fom ECS.Easy Install.

Thanks! I appreciate it!

Terry

Well, those numbers didn't compute at Autozone, so I went to the El Camino store and found them.:nanawrench:But, I may have found the real problem! I saw their "Air Conditioning Vacuum Control Pod", the round ball, and remember that when I changed engines, I did away with the cruise control, and I think the 1/4" vacuum hose from the ball attached to the cruise vacuum somehow. Now the line is just hanging, not attached to anything.
I probably don't even have vacuum!:dontknow:

yeah those were ECS #'s.I didn't look up the Azone #'s as they didn't have the one part,so like I just ordered them both from ECS.

Well, if it ever cools down under 106 I may be able to tell better if I need 'em or not. I still have cooler air on the floor than out the dash, but all the vents are working now!