2001 Chevy Tracker cycles on and off

if your sure the refrigerant is high enough then check the pressure switch, when the refrigerant isnt high enough , there will not be enough pressure and the clutch will cycle on and off, if you are filling it your self, sometimes the gauge is off, so as your filling it and the a/c is running. as it gets full enough it will cycle lesss and less untill it only cycles like once a minute if that.

approx. how many oz. of refrigerant should be put into a system?

that should be indicated on the little sticker in the engine compartment, right by the hood locking mechanism.