General Maintenance & Repairs - Help me with my air conditioning woes :(

For the first half of the summer I have been driving around without a/c because one of my lines was cracked and I couldnt find a replacement. Low and behold I finally found on on ebay. Fixed it charged the system, air blows freezing cold, problem solved right? No, now that my a/c is fixed when its on a terrible screeching sound comes from the compressor. Sounds like a belt. I tightened the belt it still makes the sound, I sprayed some wd40 on it and it stops until it dries. The sound does not occur when the air condition is off. What could this be, whats the fix?

Sounds like it might be the compressor clutch.

Needs a compressor. Don't even bother replacing just the clutch its more of a headache than its worth. More than half the time it isn't aligned properly. I'd put a new pulley bracket on it too they can make noise as well.