The AUX fan should spin freely. There are a couple of common reasons why the compressor won't run. In no particular order: Low refrigerant charge. Blown fuse in clutch circuit. Burned-out clutch. Seized compressor. Troubleshooting these is very straightforward with a multimeter. I'd go the fuse route first since the seized AUX fan prolly blew its fuse and may have disabled the system as a precaution. You'd have to follow the wiring diagram to see about this for sure though.