Can somebody explain to me how exactly all the vacum switches turns on the A/c in a car for a 69. I dont get how it uses vacum and some relays and switches please clear me up. I would think you would have to turn a button on to turn on teh compressor but i dont understand how it all works.

Also i have 2 lines comign out of my firewall there both black vacum lines. 1 is about 1 inch in length the other probably 2 feet and has a weird little circle piece of plastic all molded into the end of it

[This message has been edited by Tomb7us (edited 01-13-2003).]

Let me check a few resources to verify a couple of things, and I'll try to give you an answer.

Be right back.

Jim

The vacuum lines only supply vacuum to the A/C-Heater controls to operate the vacuum control motors (little silver pods, not really electric type motors). There are no electrical switches that are operated by vacuum. All the electrical switches are operated by the lever positions of the A/C-Heater controls.
If it's all factory stuff it'll be easy to troubleshoot and/or fix/figure out.
If someone's changed stuff over the years you'd do well to assume everything is wrong and start from scratch.

Good luck,

Louie

Of the black vacuum lines, the short one goes to the vacuum tank on the evap. case and the longer one goes to the heater valve on the passenger side fenderwell.

Jim H
69 Malibu

Louie is correct that the vacuum only operates the pods. The slide lever for your hvac controls pivots within the control head assembly, and the far end rotates a cam-like plate. This plate ports vacuum to the different pods (vacuum actuators) through the vacuum hoses behind the dash. The top of this looks like a small distributor cap with hoses coming out of it. These hoses go to all the different pods for your dampers. The only part that rotates is the cam-like piece.

The electrical portion is operated by the blower switch (heater switch). There is a resistor bank located near the evaporator case, and by selecting a different speed, you are selecting a different size resistor to change the blower speed.

My earlier reply to 81shroom may have been a little misleading, and I appologize. I looked through my Hayne's Heating/Air Conditioning Manual, my Hayne's Chevelle/Malibu Manual, and my '72 Motor's Auto Repair Manual to try and make sure I had the right info.

My only question is: "Where in the h*** are the vacuum diagrams?" http://www.chevelles.com/forum/confused.gif I turned EVERY page in each book, but couldn't find one, http://www.chevelles.com/forum/mad.gif and the underhood sticker is long gone.

Good Luck,
Jim

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Slower Traffic Keep Right

The A/C wiring diagram and the A/C vacuum hose diagram are on a couple of pages in the C60 option section of the factory assembly manual. They're not in the regular factory service manual diagrams.

Louie

thanks guys that helps i just need to findout whats still disconnected! http://www.chevelles.com/forum/smile.gif