HVAC control wiring

[JustABuick]

Hey all, I'm working on getting my heat and AC controls in, but the two vacuum lines I'm holding up in the picture seem to be doubling back through that plug hole in the firewall, but that doesn't seem right to me. Any input is greatly appreciated

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[JustABuick]

 

[Nick Micale]

One of those lines supply vacuum to the control unit, the other supplies vacuum out to the heater control valve when selected.

 

[JustABuick]

Should it be doubling back like that?

 

[Nick Micale]

Should it be doubling back like that?

I do not know what you mean by that comment?

GM designed this system, I only answered your question.

 

[JustABuick]

haha. I should probably put up another picture. Those two vacuum lines connect to that black plug, that goes through the firewall. One end of those vacuum lines (with the tape) goes to the HVAC controls in the dash. The other end is connected to the front of the plug that faces outward. It seems like those lines should go from the HVAC controls through the plug, and to something in the engine bay, on the AC box. Instead, it looks as if they go from the HVAC controls in the dash, to the plug, then immediately back inside the car, as if it's a pointless loop?

 

[Nick Micale]

It is not a "pointless loop", the vac for the heater control valve under the hood is only activated by the control head when selected.

I know exactly how this is set up as I have dealt with these AC systems for years and just went through this vac routing in detail the other day for a GN system that has no supply vacuum at the controls, and I showed the customer the exact parts in your pic.

Should I add that I have been working on these cars longer than you have been alive!

 

[Raeban]

The purple goes to the 3 port check valve by the back of the drivers head and the other goes to the heater control valve as mentioned above.

 

[JustABuick]

It is not a "pointless loop", the vac for the heater control valve under the hood is only activated by the control head when selected.

I know exactly how this is set up as I have dealt with these AC systems for years and just went through this vac routing in detail the other day for a GN system that has no supply vacuum at the controls, and I showed the customer the exact parts in your pic.

Should I add that I have been working on these cars longer than you have been alive!

haha, I am very grateful for your expertise, too!

The purple goes to the 3 port check valve by the back of the drivers head and the other goes to the heater control valve as mentioned above.

View attachment 229074

I'm going to reference that diagram frequently, thank you!

It turns out that the white clip holding those two vacuum lines was reversed (in the plug) so all of it was backwards, really throwing me off. All of the info helped. Thanks guys!

 

[Nick Micale]

haha, I am very grateful for your expertise, too!
........................ Thanks guys!

Glad to help, and also appreciate your sense of humor!

 

[JustABuick]

Glad to help, and also appreciate your sense of humor!

The car isn't up and running yet...gotta make it fun somehow

 

[Nick Micale]

It seems many people take themselves and life too seriously and end up not having much fun in life?

I am one of the "weird" ones that enjoy driving my turbo cars, but also enjoy working on mine and others as well!

Good luck with your GN, and hope you enjoy it soon.

 

[JustABuick]

I'm guilty of taking it too serious, sometimes, haha. Oh I enjoy working on it, but I bought it as a roller and haven't been able to drive it yet! Thanks, I'm sure I'll enjoy it