so when i got my 90 in march the a/c worked great then maybe 2 months ago it would go to defrost on accel. which i figured was the vac system not getting enough vac from the resivior. well now it only is on defrost vents its cold but only on the wind screen. i have to check my lines but is there any thing else that will cause this issue

 

I had the same problem on my '90 a year or two ago. I checked all the lines, checked the reservoir, etc. Finally decided I was going to have to tear into the dashboard (oh, dread!). Did all that, too... found nothing. Looked back under the hood, and somewhere under the coolant pressure tank ....how the hell did I miss that!?!? A little nick out of the hard vacuum line, a hole.


Moral ..... keep lookin'. A hand vacuum pump with gauge that will hold vacuum until you release it is helpful.

 

All it take is a small vacuum leak. Did you check the vacuum ball for a hair line crack?

 

No but I will use the smoke machine at work

 

When I put the hand vacuum pump on the main line coming off there, rear of the TB, I have a small leak somewhere. I havn't gotten as far as attataching it at the "Y" under the coolant bottle to isolate if it's the Vac disco "plumbing" or elsewhere.

 

Move it from the bumper to under the coolant pressure tank......

 

My ball is a large pill shape in the bumper. My vac disco was never there as it came factory witha 242. But ill check all that stuff

 

So smoked the canister it's good smoked the intake line it's good. Smoked the line off the Driver side canister good. Smoked the left side and found a leak at a vac line going into the fire wall broken replaced it and now were back in action thank you all

 

That seems to be a common place for failure of the plastic line.

Still gonna drive around with your ball in the bumper?

 

Can someone please clarify...."left side" meaning the small plastic line on the right? (from the ball).

Supper you found it!...I still need to chase mine down.