This morning my buddy brought over his 98 s90 and when i turend on the front window defrost the AC didnt click on like it should, about a minute later it came on, but only for about 30 seconds before shutting off and coming on again a while later. I checked the freon level and pressures are looking good. However when i was driving it home from school the AC worked fine on all settings. It was quite cool out this morning, sowould this have anything to do with it not coming on properly... ive ruled out alot of electrical problems by swapping the climate control unit with another one i had lying around and everything worked fineas it should....
Ive had enough headache with my 960 AC; which by the way has worked like a charm for over 4 months hastle free.... it only took a new condensor, evaporator,high pressure suction line, drier and expansion valve and about 6 or so cans of 134 to solve it!! - im hoping we dont have to go through this again.

 

Behind the lower dash panel and knee bolster(Metal bar) There is a electronic vaccum control. Check the solder joints on it.

 

In addition to this problem there sometimes the selector switch for the air vents would not work. So we took that dash apart and there is a wire harness with lots of wires, i found when i would wiggle it around things would work again. I pressed the harness tight and used a zip tie to hold it that way... As for the phantoem AC problem, I started with the electrical system and found the compressor relay to be the culprit.... $12 dollar fix
Thanks again Tech!