[Shotimes] AC question

[Mike]

Well I haven't been paying as much attention as I should have......my '95's
AC will usually blow me right out of there, even around 100F.  But it is
starting to suddenly get warm once in a while, and I have the feeling its
the clutch.  What is the procedure to check the shim, and what needs to be
done in this case?  As I recall a shim has to come out?  Can this be done
with the compressor in the car?  Do I need a belt-type clamp to hold the
pulley from turning?  A quick procedure, please.
Mike