Fan motor on outside unit is always on even when set temperature is reached

Not knowing the manufacture of the unit, it may very well be a stuck contactor, holding in the power to the fan motor. And at the end of the call for cooling, the contactor drops out only the compressor. This is not a troubleshooting problem that a DIY person would want to play with, due to the 220 volts at the contactor... NOT something to play with ! A good contractor can evaluate this issue and make the proper repairs...