!992 PU A/C

I have the 1992 PU with the V-6. Great vehicle however since the day we owned it the A/C has made a horrible vibrating noise when the compresser kicks in. When it was under warrenty the dumb dealrship replaced the compresser and who knows what else and eventually threw their hands up in the air and walked away from it. Isuzu eventually took the Isuzu dealership away from this guy and us Isuzu owners were left stranded here. (I live in Hawaii, no other Isuzu dealership on the island and we can't drive to one) . But anyway we didn't have this board back then and I am sure that this may have been a common problem. Any experience out there to share?