69 Barracuda heater control vacuum lines on firewall

[Orange Peel]

I have a question reagrding the heater control vacuum lines coming out on the firewall.
Does anyone have photos or diagrams of what and where they connect to?

I tried searching other posts but couldn't find any that had 3 vacuum lines coming out, only those with 2.

I have a 1969 Barracuda with a 318. It is an A/C optioned car but the A/C system was tossed along the way.

Here are some pics of what I have to work with.

 

[Cuda68Scott]

On my 68 the 2 bottom one go to the heater hose valve, and the top one goes to a fitting on the rear of my intake manifold. I have a 68 a/c 318.

 

[Cuda68Scott]

Firewall with 3

 

[Cuda68Scott]

Two go to this heater hose valve:

 

[RedFish]

There should be a vacuum reservoir inline also. You can block off the 2 that went to the hot water valve. You will need the vacuum supplied to the push button controller ( and reservoir ) for directional door servos to work.

 

[Orange Peel]

So can I connect the unblocked line that's left to direct manifold vacuum or does it have to go to the vacuum reservoir?

 

[RedFish]

I think the reservoir has 2 ports on it. You don't absolutely have to have a reservoir.
Default position for most of these plenums is defrost. So whenever there is a drop in vacuum like hard acceleration, the doors begin to go to the default position.

 

[equium]

I'm dealing with the same thing on my 70 Valiant.
The previous owner had no vacuum lines hooked up.
I identified the 2 lines to the water valve (My AC is gone too).
The third line, as i'm learning here, is the vacuum source. Mine has what appears to be a brass connector on the end. Did the factory vacuum reservoir have a connector like that?
It's obvious I need to connect my vacuum. Do I just pick an open port on the carb?
Thanks for letting slide into the conversation.
Danny

 

[Cuda68Scott]

I cannot remember if my stock 318 intake manifold had a vacuum reservoir or not. Anyway my 3rd line just hooks to a vacuum port on the rear of the Offy dual port 360 manifold that is on currently. It has been a long, I mean loooong time since my car has operated but I think when it did, the air control worked Ok. I do seem to recall having to change out the air switch in the dash a few times and seem to remember that was a PITA.

 

[equium]

I cannot remember if my stock 318 intake manifold had a vacuum reservoir or not. Anyway my 3rd line just hooks to a vacuum port on the rear of the Offy dual port 360 manifold that is on currently. It has been a long, I mean loooong time since my car has operated but I think when it did, the air control worked Ok. I do seem to recall having to change out the air switch in the dash a few times and seem to remember that was a PITA.

The PO installed a Mopar high rise manifold. I don't know if there are any vacuum ports on there (it's dark outside). If not, i'll just attach to the carburetor.
I do know that once I re-connected the heater hoses to the core, I got warm air from the AC vents. (That's how I figured I had a vacuum issue, and also no air went to the defrost ducts when DEF was pushed).
thanks,

 

[RedFish]

Defrost may not be default in this particular case. Reason being, majority of actuators/ servos used are a single line vacuum over spring type.
Chrysler engineers used several dual vacuum (no spring ) servos. When vacuum is lost, these could stay in last called for position unless another force causes movement.
Dual vacuum servo at hot water valve is one example. Take away its vacuum and water flow could push the valve open.

 

[1994redram]

My 70 dart also has 3 lines. Two to the heater valve and the top one to the intake manifold. My car is a slant 6 factory air. It doesn't have a vacuum reservoir. And I don't see where one would have gone. On my 73 camaro I did default to defrost when it lost vacuum. Everytime I went wide open throttle I would lose air through the vents until I let off the throttle. A simple little vacuum check valve fixed that problem. The dart does NOT default to anything. It simply stays where it was when I lost vacuum. So I haven't had the need to install a check valve.

 

[qkcuda]

Sorry I'm late to the party. My cuda has 3 lines a well, a vacuum supply to the intake (with the white fitting in it), one with a red tracer to the engine side of the control valve and one with a white tracer to the fender side of the control valve. Here are a couple of pictures.

 

[Orange Peel]

Thanks for the feed back and pics.
Winter hit early so the car is already under wrap.
I am going to try and source out a vacuum canister over the winter. If any one knows where I can find one please let me know.

 

[easyrider]

Where can I find one of these duel servo heater control valves? Part #?

Tom