I rebuilding a 69 Malibu. Originally 307 w/ auto, factory air. Unfortunately, I've found during the process most of the heating/ac parts have been scavenged; ductwork, vents, vacuum lines, wiring, etc.

I thought I had everything tracked down and am now in the process of putting the puzzle back together. Then, I noticed on a diagram in the Assembly Manual that there is a Vacuum Switch located on the heating control unit. Mine, of course, is gone.

Can anybody tell me if this switch in necessary or if it can be bypassed somehow or substituted with something else? If I do need one, where I could find one? I've looked on line at Ground Up and other suppliers but haven't been able to locate one.

I sincerely appreciate any help on this. Trying to get the dash all buttoned up so I can move on to the rest of the interior.

Thank you, Ron

My 72 has 4 inside, the 68 I just took apart was all electric, no vacuum.

The wiring diagrams I have give diagrams for vacuum lines, and the control has the threaded holes where the vacuum switch should go so I'm assuming the lines are required on my system. Anybody know for sure?

Yes you will need the vacuum switch to make it all work. The '69 used vacuum to control the fresh or recirculate air flow. The flapper door up in the right side of the cowl and the vent in the passenger kick panel.

I seem to recall there being another vacuum operated feature on these as well... but cannot remember exactly what it was off of the top of my head.

There is also a rather unusual electric switch mounted on the control assembly as well.

I have also gotten the impression that not all '69s are exactly alike here. But the vacuum air controls were used on all of the '68 and '69 cars.

BTW here is somebody who is very proud of theirs:

http://cgi.ebay.com/ebaymotors/69-1969-CHEVELLE-HEATER-A-C-CONTROL-RARE_W0QQcmdZViewItemQQcategoryZ10076QQihZ015QQite mZ250145758485QQrdZ1QQsspagenameZWDVW

Yea, that's what I was afraid of. Been going nuts trying to find one and I've been watching this particular setup but I sure hate to pay that kind of money for just a little switch.

If anybody knows where I might be able to find one, please let me know.

Found the part I was looking for today. I purchased and entire heater control with the vacuum switch. Control is in better shape than the one I had.

For fellow Chevelle owners in the Bay Area, check this place out. Nice operation, clean showroom, very organized.

http://www.gmsportssalvage.com/

Well, if anybody can help me out I'd greatly appreciate it. I though I had is solved but it turns out that the controls for the 68 and 69 are slightly different.

The control I bought to salvage the vacuum switch from is from a 68 and the vacuum switch only has 2 ports for hoses. The vacuum hose harness I bought has 3; one for incoming vacuum, one for the fresh air doors and one for the water valve.

Does anybody know where I can find a switch for a 69 or if I can "T" in the water valve line to the fresh air line?

Thanks, Ron

You might be able to run it like the '68 with the heater core always active... perhaps with a manual shut-off valve up front for seasonal use.

Thanks, Steve. I wasn't sure if the ports opened at different stages when the switch pivots so I didn't know if that would work.

I lucked out though. I returned the control to GM Sport and they were able to dig up one for a 69 and exchanged it for me.

I also located a nos one on ebay and it is on its way. If anybody needs a good complete control for a 69, let me know...