Gary,
It's not often that I disagree with you, but a low refrigerant charge will normally allow the compressor to run with very little additional sound above that of the fans/blowers, but no cooling will take place. Some a/c's, particularily automotive systems, will not even try to engage the compressor if the refrigerant charge is too low. A system that cycles on and off within the times you mentioned, without actually starting the compressor, usually indicates a too high head pressure, which must be relieved before the compressor motor has enough energy to overcome the starting resistance.
Yukon3506;
If the problem is a low refrigerant level (a leak), there's nothing you personally can do about it. It's a sealed system, and without the proper tools/gauges/brazing equipment, there's little you can fix yourself. As Gary said, if it is a leak, you're better off replacing the unit than trying to apply bandages to an old wound. If you're comfortable with electrical circuits, you could try jumpering the thermostat to see if the a/c is working or not. It's not difficult, and the voltages you'll encounter will be in the 12 volt range - pretty much harmless. May be worth a try, and you may save yourself a few hundred dollars (if it's the thermostat).
Good luck!
