1997 Mercury Marquis Compressor

I am having problems with my A/C Compressor. I recharged the system with R-134a. The compressor finally kicked in, but only works for about 5 seconds then cuts off. About 20 seconds later it starts again, then cuts off. I do not hear any squealing from the belts, and the compressor sounds ok when turning. Do I have a bad clutch, or is there a bad sensor somewhere. Also, it blows very hot air when on Max A/C. Thanks