What is this and does it need to be hooked to a vacuum source
 

Looking around behind the glove compartment area as I started putting my dash together I saw the heater/ac box with it's vacuum lines and manual controls... I followed a vacuum line that went through the firewall to see where it went and it was connected to the small round canister near on the firewall above the heater core lines. It also had a larger diameter hose coming out of it which I traced down to the A arm, dangling and unconnected.
I am assuming it's a vacuum canister for the heat/ac stuff in the cab but wanted to make sure.
Also, am I right in saying the line/hose coming out of the canister needs to be hooked to an engine vacuum source?

Re: What is this and does it need to be hooked to a vacuum source
 

In a word, YES. The cannister you see is a reserve for the AC & heat doors when you accelerate hard and vac drops. Hook it up to any manifold vac source. jim

Re: What is this and does it need to be hooked to a vacuum source
 

Thanks, will do. One question though, with it being disconnected does that mean the controls would not work properly if at all?

Re: What is this and does it need to be hooked to a vacuum source
 

The modes would be switched and possibly frozen into the defrost mode only (default) for saftey reasons. The mode switch (vacuum valve) in the control head gets it's vac supply from the reserve cannister. jim

Re: What is this and does it need to be hooked to a vacuum source
 

ok thanks for the info