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Discussion Starter #1
Hi all, I am trying to confirm the use for the two vacuum lines running off the three-barbed tee by the AC accumulator. One is gray and one is black, and both go into the firewall. I'm assuming at least one is for the AC. I found this thread, but it doesn't confirm anything:

http://www.tccoa.com/forums/showthread.php?t=48385&highlight=Gray+vacuum+line&page=2

If both relate to AC, am I able to cap off the barb on the main (white) four-barbed tree that runs to the smaller, three-barbed tree if I've removed the AC system, or will this affect my heating/defrost capabilities?

I have a few images for reference, but am new to posting on the forum and the inability of new users to host images here is frustrating (I'm well versed in HTML), but will do my best to get those images up for future searches. Thanks.
 

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Discussion Starter #3
Thanks for the input. I don't mean to be a butthead here, but you're a bit ambiguous in your response, care to expand? If one line is for the HVAC, then AC would most certainly be included, correct? Additionally, if the other line goes to a vacuum reservoir (is that the technical definition by the way?), my best guess is that the reservoir is for...the AC (or possibly the whole HVAC system as you say) during acceleration or WOT.

Regardless, the end game here is knowing the effect of capping the small line from the main tree that feeds these two other lines, considering I have no AC, and still being able to retain heat/defrost capabilities; otherwise I would like to replace the shoddy stock plastic lines.
 

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Discussion Starter #4
Also, I believe when you meant HVAC system, that is to say that the controls to switch between dash, feet, and defrost vents are vacuum operated? If so, this solves my misunderstanding.
 

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1994 Cougar XR7 DOHC/5-Speed
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Sorry, The grey line is the main vacuum feed for the whole head/defrost system. With it gone you can't operate any of the settings. You're correct about the reservoir(pretty sure that's the technical name, never thought about it lol), it holds a vacuum supply via a check valve(inline with the vacuum line) so the system functions in the low vacuum conditions you mentioned, it serves to smooth out operation as well.

I probably shouldn't have said HVAC controls, since that acronym has A/C in it. To rephrase I would say those lines are for the climate controls. Still vacuum is unrelated to A/C since the vacuum is only used to operate the various doors in the dash, weather it's heat or A/C.
 

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Discussion Starter #6
Perfect. Thanks for clearing it all up! When you wrote vacuum reservoir in the fender well, I wasn't sure if you perhaps meant the charcoal canister for the evap system as I know that draws vacuum as well. Thanks again, sir.
 
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