This started yesterday leaving wrk. When I turn my air on, the compressor makes a loud noise while it'* on like metal grinding. Should I just replace the whole compressor or is there something I can do to save this one. I've had it for 6 yrs now. I'm sure it'* still the original compressor.

Its the clutch more than likely.
Recommend replacing the whole compressor. But I HIGHLY recommend a shop do this. The freon needs to be evac'd properly, then the compressor is changed out, then there is a vacuum put on the system, then the freon is charged per spec.

What Mike said ^^^^^^^

And/or it could be the guts of the compressor going bad. Whatever you do, don't run it any more until it is repaired. The whole system will need to have all of the metal bits cleaned out. If there is enough in there, they may plug the condenser.