the a/c in my girlfriends firebird 3.8 has been out for the longest time and its getting up into the triple digits lately.

I was told that the problem was the seal on the compressor shaft, is this a common problem? if not where should I be looking?

also how hard is it to remove the a/c compressor?

 

Changing the compressor out is no big deal, but the system will have to be properly serviced. Such as evacuation with an AC vacuum pump, receiver drier replaced, proper type of oil added, system checked for leaks, all the seals probably dried out by sitting unsued for such a long time, system properly recharged, plus many other things that will crop up.