On this diagram, and on every other diagram I've ever looked at, it shows the HVAC vacuum, but never shows where it hooks up to. I bought the car with this connection plugged up and have never been able to get my A/C controls to work being that it isn't getting vacuum. Can someone explain where the very rear connection on the passenger side of the intake plenum hooks up to?

Thanks.

 

I think it would hook up to, the very rear connection on the pass side of the plenum.

The legendary Orb Of Power, which is actually just an accumulator, so that the accessory vacuum doesn't instantly disappear when you floor it, like it otherwise would. It is at the lower left of your diagram. The blue line you show goes to the large port on it, and the purple line from the HVAC should go to the small port on it.

 

There are two connections on the cruise control servo, the bigger of the two runs directly through the firewall of the car, the smaller of the two runs from somewhere over near the distributor, and is teed off to hook to the ball mounted behind the front bumper cover. this all looks like it's hooked up properly, but I still have a port on the very rear of my plenum (the bigger of the two) that says it's supposed to go to HVAC, but it's plugged off with some spare vacuum tubing with a bolt in the end of it.

 

Viprklr referred to it in this post as "a hard vacuum line coming out of the firewall for the HVAC." a more specific location of where on the firewall I should look is what i really need, as I have a feeling it's missing or VERY well hidden.

 

In another post of his, he mentions a 3 way check valve. I'm hoping that's for 90-92 year models, because I have no 3 way check valve.

 

I've found two vacuum lines going through the firewall, they are running in there inside a wire loom with a bunch of other wires.

They WERE hooked up to:
1 of them was hooked up to the heater control valve.
1 of them was running straight to the power orb and cruise control servo.

someone please help me out with which one goes where and what *should* be in between? note: I removed my heater control valve today so I have 2 vacuum lines to play with now if that helps?

Thanks.

 

That sounds correct.

There should be 2 lines inside the harness that comes through the firewall by the heater core. That's the AC harness; it's a self-contained unit, totally separate from everything else about the car, it's just part of the AC system and nothing else. It gets power from one wire under the dash, and vacuum by one of those lines.

One line should be white, and goes to the heater control valve, and the other should be purple. The purple one should go to the Orb. If you removed the heater control valve, plug that line with a golf tee or a screw or something.