I had problems with my 92 960 A/C whenever I accelerated or went up a hill. I figured that was due to the drop in vacuum on acceleration and a combination of leaks under the dash in the HVAC system. I remedied the problem by going to Pick and Pull and purchased a vacuum storage tank from a Saab. I mounted it under the hood and put it in series with the vacuum lines to the HVAC. The vacuum line from the engine has a one way valve so that when the vacuum drops on load the tank maintains it's vacuum. Problem solved without having to tear the dash apart and chase down leaks. I did this about 3 years ago and even though I don't own the car anymore, I live close to the new owner and he tells me it is still working perfectly. As for your compressor cutting out could it be from your cooling fan? In hot weather the fan should cut in when the compressor kicks in and if it doesn't, the A/C system will shut down due to the system pressure being too high. Hope this helps, vacuum storage doesn't cure the disease but it alleviates the symptoms!