My AC is not cooling. I got a can of refrigerant to recharge it, but then I noticed that the compressor doesn't seem to be kicking on. My questions are... (1) How do I confirm if the compressor is totally dead? (2) Is it possible to replace the clutch only or is it an all or nothing type deal? I'm just trying to find out if I just need to replace the whole compressor, or if just the clutch is bad and if it's possible to just replace that? Thanks.