Breaker tripping when the outdoor unit comes on??

This should give you an idea on how to check a PSC motor for a "short to ground". A grounded compressor is pretty much a done deal and easy to diagnose. Just follow the steps here.

I am not sure if you will come across an old enough compressor that would need to have individual wires at each terminal but you can use your multimeter to determine where the Run and Start windings are on the compressor by checking resistances between the terminals.