My wife'* Bonneville has been having progressively worse AC problems for a while now. It started with the compressor becoming increasingly noisy when activated and then finally ceasing to cool the air or engage altogether. When I tested the freon pressure, it came up as nonexistent, so I pumped it full of freon again, and voila the compressor started working again (I assume it had some sort of low pressure shutoff feature). But even then, the cooling was nothing to write home about. Maybe a third of what it used to be. Just recently, despite keeping the pressure up, the compressor stopped engaging again. The pressure in the line is around 40 psi which tells me that freon is not the issue, the compressor is. Does this sound reasonable? I haven't spent a lot of time working on automotive AC problems, so I want to verify my thoughts on this. THe system does seem to lose pressure slowly over time, but it isn't gushing out freon. I just gave it a charge with the UV dyed stuff so I can find the leak, but I'm not sure that will work if the compressor won't engage. Am I looking at needing a new compressor or is there a quick fix to this?

Just so you have proper info, a competent shop would put leak detecting dye in your system, and check for evidence of this dye leaking some time in the future. Freon has to go SOMEWHERE. If the leak is at your compressor, then the likely diagnosis would be to replace the compressor.

Your compressor is also a candidate for problems since it was making noises.

Is replacing your compressor an option?

That'* what mine required.

Yes. Before when the pressure was zero, the compressor kicked on when I hit 25psi. Now it hasn't kicked on as of 40 psi.

I will try a little more freon tomorrow, but more than 45 psi is listed as too much pressure, so I don't want to go much past that.

The freon I added today has a UV dye in it and I have a blacklight ready and waiting to find where it'* leaking, but since the compressor won't cycle, it can't get to the rest of the system. I have no problem with replacing the compressor, but I want to make sure that is my problem before I do. They are a little spendy.

So I was able to get the compressor to kick over once I added more pressure to the system. It just needed more than I originally thought. So I added the rest of the can of dyed freon to the system and looked for leaks. No dice. However, I could hear a hiss coming from the area of the compressor. That was Monday night. Now I'm back to thinking the compressor is the issue. I checked it again tonight and it had lost enough pressure that the compressor wouldn't kick on again. I put another can of dyed freon in and looked around with the blacklight and there is no sign of leakage anywhere, except for the hiss that I heard the other night. I pulled out an old stethoscope and listened to every part of the system and the only place the hiss became pronounced was when it was on the front of the compressor pulley. I'm guessing the leak is underneath that pulley, probably at the input shaft seal where I wouldn't be able to see the dye with a blacklight. So although the compressor works, it leaks and to my knowledge rebuilding it is more trouble than its worth.