AC compressor keeps blowing fuses, any ideas on probable cause? System is charged and cools well until fuse goes.

 

The compressor and the condenser fan are on the same fuse, so it could be either one doing it. Or it could be an intermittent short to ground in the wiring itself. Check that the fan spins freely by hand, if it binds up it will draw too much current and blow the fuse. Resistance through the compressor (from the clutch wire to ground) should be 3 to 4 ohms. If it is less than that, the clutch coil is partially shorted and needs to be replaced.