Please someone help me. My central unit compressor sounds as if it is trying to kick on but doesn't start up completely when turned on. The fan turns, but not at full speed and after a few minutes, the fan stops and then the compressor makes a bad noise. Sounds to have a slight squealing sound on top of the hum that it already has. What is wrong? I can't afford a new unit. Please quick, before everyone closes at lunch today.

Sounds like you may need a new capacitor. Around $25 . Check to see if the top is swollen in any way or the wires are burnt.

http://img.diytrade.com/cdimg/377701/1688670/0/1132835703/AC_Capacitor.jpg In the outdoor unit.

Thank you very much. It was the fan motor. Got in touch with someone that works on a/c and came right on, diagnosed and replaced. :)