Could be anything from low refrigerant, bad pressure or clutch cycling switch, bad compressor, or other electrical problems. You just have take the time to diagnose and find what isn't working like it should. The first thing I'd do is check the refrigerant and get it where it should be. The next thing I'd do is make sure you got 12 volts at the compressor.
Loose nut behind the steering wheel.
It's broken - won't heal itself - you'll need to have it repaired.
