Yeah I have. Gonna try that but I was just thinking it would be easier to replace what I got as the only vac canister i can find is right on the eng compartment wall and easy to get to. I'm just not sure thats it....

 

Well, went and got a "tomato juice" vacuum can from an old ford pickup from scrap yard for 5 bucks and the check valve recommended in the link for "cheap easy fix" and it seems to have done the trick. I accelerated hard and even slowed done before a hill and accelerated up it and the ac stayed on vent the whole time. I used a plug i had from working on an old truck before to plug the other port in the new can. Thanks guys
Is still rather luke warm in the back tho, that probably because the blend door in the unit for the back is not quite fully switching to ac? here's a pic of what i did. will mount can down below air intake there is actually lots of room

 

I like it!

 

Glad it worked out for you - I made my reservoir out of 2" pvc pipe about 8" long if you have to make one later. I think the ford factory reservoir is behind the heater core, so the bypass is the easy & cheaper way to go. I put a longer piece of hose & installed the new reservoir on the drivers side front . It was a good open spot in my van.

 

Rear and front air ducting is controlled via the same vacuum signal---if the vacuum servos are operating correctly up front then the rear blend door needs to be checked for operation. It could be stuck in place, vacuum lost along the way from the front or the servo itself has failed.

 

Thanks JWA