AC Comp loud in engine/shops near Worcester

[William Allison lll <wallison@bbn.com>]

What is the diagnosis on a very loud AC compressor (I am assuming here)
nosies coming from the forward portion of the drivers side engine
compartment?  Happens when AC compressor is cycling on.  Fixes?
Torubleshooting tips?

Thanks in advance,
Bill 
86 5kcs 176K
90 745 GL 87K

P.S. I can recommend one shop in Ashland (halfway between Boston and
Worcester) that specialize in Audi.  Ashland Foreign Motors on Alden St.
Nice fixes for alternator, electrical-windows etc.