This is kind of "down and dirty". What I did to test the clutch was, locate the two wires that come up from the compressor through the intake manifold. Then, using a nail or sharp instrument, puncture the insulation to contact the wire. Run a wire from the battery to the nail and the clutch should engage. I don't remember which wire it was (I'm thinking yellow, but I could be wrong), Try both. If it does not engage or engages very weakly, then it is bad. It should engage with authority!