[psomers]

To safely discharge a capacitor short the two terminals together. That is with power off and holding the insulated handle of a screw driver. Capacitors in AC circuits don't normally have a charge like it would in a DC circuit. Capacitors in AC are normally for phase shift of AC to help start motors.
A bad starting capacitor will cause high current trying to start just like a bad compressor. They will usually hum and over heat very quickly.