Hi my name is Pete and I am very new. I have diagnosed a bunch of things on our 1997 960 and I am down to just a few now. I had some way hot radiator 2 fan relays and fixed that, added a can and a half of R134A but The A/C is a little low, 28 lbs or so at 2000 rpm. I haven't added any more refrigerant yet, but here's what it does . The system works great on automatic or manual climate setting first thing out of the garage in the morning. When I get to where I'm going and I shut it off the car, go get coffee or whatever, and come back and start the car the compressor never kicks in again..it makes one failed click and it is out. The previous owner appears to have totally disconnected the thermal cutout sensor on the side of the compressor and left the direct wire to the clutch alone. It has the thermal diode thing (square black epoxy filled resistor switch)? inline still. Before I bypass this am I OK to do that and does it sound like the culprit? I would rather not do a failed undo.. I suppose 4 mor ounces of freon may do the trick too but we never used the A/C when we first got the car and I doubt it worked properly then.Any insights would be greatly appreciated. I searched the threads and have formulated my ideas to this point but smarter than me is what I need now

 

Systems seems to be operating properly. First things first -- your low-side pressure is too low. As car warms up refrigerant loses pressure and falls below the low-pressure cutout point. Especially when you stop this even worse since there is no more cooling at the condenser.

You need to up the pressure first. If pressure falls out in a few days, you have a large enough leak that you need to find and fix.

 

Thank you for the quick response. I had already done all that. I took the car to an A/C specialist and the high side MAP sensor had failed.It was looking for ground and shutting the compressor down. A small chunk of the yellow "O" ring had gotten lodged by a previous someone. Got another sensor at a salvage yesterday for $1 and it's fine now. My freon level was actually within 2 ounces of perfect. Ah..the Volvo. Happy now! Pete