I'm reasonably sure you shouldn't be able to spin the driven spindle of an A/C compressor by hand. The compressor clutch has two major components. The drive pulley is turned by the serpentine belt. The compressor shaft pulley is driven by the outer pulley when the clutch is energized. If you can turn the compressor freely, then there is no freon in your system or the swash plate has broken off the compressor drive shaft. As Donnie said, check the R-12 to see if you've got any..
2000 Dodge Grand Caravan SE