A/C Vacuum Leak, NOT the Cannister

I have elliminated a few things from my "A/C only through the defrost vents issue". After reading many posts, I assumed it was going to be a bad cannister. It wasn't. I went ahead and purchased a vacuum pump and guage. The vacuum cannister holds 15in just fine. In fact, at the "T" under the hood, I can read 15in even at idle.

When I seperate the vacuum connector behind the glove box, I can use the pump to cycle the A/C through all settings. They all seem to need about 15in to fully engage. The problem is that the vacuum line coming into the switch (black) has less than 5in on it at any time.

Does anyone know where the black vacuum hose originates at? Where does vacuum come through the firewall? I can't seem to find anything loose or leaking under the hood.

On a side note, in all my searching, I seemed to make it worse. The recirculated air mode was working before I started, now it doesn't either. With the pump it only seems to need about 5in to partially engage.

If anyone could point me in the right direction, it would be greatly appreciated.

Eric

look behind the battery

The vacuum line that "feeds" the heater controls should be right next to the heater core and evap connectors on the firewall side.

not really sure, but i used ice maker hose as a replacement its hard and hooked it up to the last place i have good vacuum and went through the firewall and hooked it to the ac controls, i couldn't find my leak neither

I actually already repaired the lines which were damaged by battery acid. I really thought everything was going to be fine because I "found" the problem.

Tomorrow, I will look again around the heater core. Most of the lines I found today, went across the firewall to the drivers side of the engine. It would make sense because I was messing with stuff around there today, trying to find it, and now it is worse.

The black vacuum hose seems to go up into the dash behind the radio. I am hoping it is not back there! I am praying it is under the hood.

Thanks for the suggestions.

The suggestion to just run a new one sounds really good too!

On mine, the vac enters the cab on the firewall on the rt side inboard from the blower motor.

there is a reducer piece there with a 1 way valve in it.. mine was in backwards. turned it around and all the vents work now.

Found It!!!

It was right where the line goes through the firewall. Can't believe I missed it so many times. A/C is running perfect now. Thank you for the input.