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I might be wrong but l think that is how it is suppose to be. You have a one way valve there,when the air is on recirculate it opens the door on the kick panel and pulls air from the cabin. When the air is on fresh it pulls air from outside the cabin. When you switch from recirculate to fresh that line allows air to enter the vacuum diagram in the kick panel allowing it to close.
Does it all work ok?
 

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Discussion Starter · #3 ·
Not exactly sure if it all works okay cuz the AC needed to be charged And I bought the car in mid October.

Everything I've tested so far works.

Just not sure why that hose was dead ended just hanging out in the cowl vent area?
 

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When you change from recirculate to fresh you should hear the air enter there to allow the vacuum diagram in the kick panel to close. Like l say l may be wrong but check it.
 

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Discussion Starter · #5 ·
Do you think that line with the screw in it should just hang there and suck in air or did it connect to something?

Just not sure why it's blocked😕
 

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Ok missed that and that certainly is not factory. Take it out and operate the system to see that it all works. Check that it's not pulling vacuum.
 

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Maybe a little one way filter should be in there and it has been broken over the years so it's just been plugged.
Do you have a vacuum line going the heater control valve? It could also be for that.
 

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Pretty sure these are the lines you are looking at. They supply the vacuum for the actuators that control recirculated cabin air or outside air. The only other 2 vacuum lines that go through the firewall are for the vacuum source and the heater valve.
 

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I have 79 with a vacuum line going to a heater hose shut off valve when on recirculate air. (Full cold).
Tom
 

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Discussion Starter · #11 ·
Yes I have the line to the vacuum control valve. All lines are in place and intact except for that one mystery one just hanging out there under the cowl with the screw in it.
 

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Do the recirculation and fresh air vents operate correctly?
 

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The way it was designed was for one line to run from the manifold ( thru the check valve) to the vacuum. From the vacuum ball a line runs thru the firewall to the HVAC control unit. A second line runs from the HVAC control unit, back thru the firewall, to the heater control valve located on the heater hoses.
 
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Font Urban design Engineering Parallel Schematic

This is suppose to be the right diagram for a 69. Do any of the hoses have coloured traces on them?
 

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The diagram l posted earlier is a zoom in of the area l think we are trying to identify. The actuator on the right in that diagram is the one located in the kick panel that controls recirculated air as per your photo.
 

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I was going to say that plugged line could have been a vacuum reservoir.
Tom
Very possible Tom as the system works correctly,that's the thing.The diagram does not show a reservoir but mine had one,it was mounted on the passenger side inner guard.
 
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