Condensor Fan or Mother Board?

Yesterday I noticed that the frame between the freezer and fridge was extraordinarily hot and the unit was not as cold as it should be. I moved the unit cleaned the coils and noticed that the fan that cools the condensor and coils was not running. How do I determine if I have a bad fan motor, loose connection, or a bad mother board? The fan blades turn freely by hand and the temp is good now that I have a box fan running behind the refrigerator. Are these two parts easy to replace for an average do it yourselfer? Thanks!