After having great experiences with two 740 volvos, I recently purchased a 1995 850 wagon for my 17 yr old daughter. Tried out the air conditioning today. The compressor kept turning on and off every 3-5 seconds and the air coming from the vent was not cold at all. I hooked an ac recharge kit to the low side port. As the compressor turned on and off the reading was 45 to 65 psi. The reading fluctuated as it turned on and off. I let out some of the refrigerant and turned on the ac. The compressor didn't come on at all and the reading was 20 psi on the gauge. The air coming out of the vent was still the same temp as before. I added some refrigerant to try and get the correct psi reading (25 to 45). When the gauge got to 25 psi the compressor began to turn on and off again every 3 to 5 seconds and the reading on the gauge fluctuated between 25 and 45 psi. The temp of the air coming out of the vent remained the same. I have no background on this vehicle from the previous owner. any help would be greatly appreciated.

I was about to make a post about the same thing (almost anyways), but figured I would add mine in here as well.

In response to your post, it sounds like you are atthe same stage I was at awhile back. I had the refigerant in there but the compressor just kep turning on and off and then would quit entirely unti I restarted the car, and no cold air ever came out. I tried using the recharge kit at the time and it didnt help anything. I then realized that the A/C unit in my Volvo (1995 850) has to be put in under a vaccum.

I took it to a local hop and had them do it properly.Once they did it blew ice cold air. The problem was it only blew cold for about 4 hours, then back to the same old thing.

At that time, it turned out my fetzer valve (low pressure valve) was leaking, causing the pressure to drop below operating range, so the car wouldnt allow it to run. I replaced the valve and had them recharge it again. It blew cold as ice again, but it would then quit working after about 15 minutes of use. I would have to let the car sit (while not running) for about 2 hours before it would start working again,and even then it would stop blowing cold after about 15 mins and I would have to repeat everything again.

I will add, that it seemed odd to me, but the people who recharged it for me, told me it was blowing super cold (33 degrees F), and I believe him, it was nice and cold...almost too cold if you ask me, but I dont know how cold it is actually supposed to be.

Anyways, about 2 days after all that when it was kind of working, my A/C no longer works at all. The compressor wont even come on anymore now, no clicking to even show that it is even trying. I havent done any looking into it, as it gave up during the winter, and I rarely use AC anyways (but during the summer with black leather, it can be an oven in the car when you get in it).

I am beginning to wonder if the clutch has simply given out on it, which will be the first thing I will check, however that doesnt solve the situation with it quitting after 15 mins anyways. To me is seems like it is blowing so cold it is actually freezing up. Unlike my cruise system I have not changed anyparts of the A/C (and it didnt work when I bought the car, but it seemed due to the leak it had at the time. There are no leaks in the system now, but it wont work at all.

I don't want to hijack the thread, but I too am looking for things to start with that I should inspect first (as I know several parts of the A/C system are quite expensive, I cant just start popping in new parts without having a reason first).

I am thinking the magnetic clutch in your compressors.