My air con compressor seized recently but so did the bearing on the electromagnetic clutch which I suspect had been on its way out for a while. My car always sounded wrong but I couldn't pin it down and I suspect the bearing in the clutch was the culprit, I'd be checking it as well as re-gassing the system. I read in the forum somewhere Scooter stated not to decrease the amount of oil but use the full amount. I followed his advice and now my one runs very quiet. The compressor cost me £250 plus the dreaded vat but this is a new one. I did try another company I'd read about on here but the guy hadn't a clue what I was talking about, all he could say was they only do the parts listed on the online catalogue