Sounds like you're about to toss the compressor; your speed sensor should start cutting your compressor out before long, but until it does you should continue to feel and hear the compressor getting worse. You might hook up a guage and make sure there is not a blockage on the high side causing the problem, however. If no blockage (I.E. pressures above 300psi w/ the aux fans on), then compressor very likely; keep in mind the friction that causes this vibration will also be causing metal to flake off and travel throughout your A/C system, possibly ruining other things as well.

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