A/c

i have a 2000 sunfire, 2.2l. the other day i want to use the a/c and i noticed it was not working, is there a way to test to see if the compressor clutch is gone, i also took a voltage reading at the compressor and i get no voltage, could it also be the a/c compressor clutch relay and how or can i test that. i get 13.5 volts at the terminal where it relay plugs in .
help please
tommy