not sure kung applicable yung approach ko sa mga experts dito. but i check the belts kung may slippage by pouring a bit of water on it while idling (ingat lang sa tubig na magliliparan). pag nawala yung sound, belt slip yun. i think this is the easiest way to check.
kung sinasabi mo naman na lumabas yun after i-mount yung compressor, baka alignment naman nya yung mali, worth checking din.
kung grinding sound, baka sa ibang parts but most likely compressor bearing kasi yun yung sinervice-an. malalaman mo yan kung gagawin mo suggestion ni kups.