No question about the GFI requirement for the receptacle in the garage. As for the "readily accesible", I suggest you read the definition of this in article 100 and draw your own conclusion as to whether or not behind a garage freezer meets the definition of readily accesible. My opinion, if it is on wheels and roll out of the way quickly and easily, no problem with being behind the appliance. If it is my grandfathers freezer that he has had since the 40's that weighs in excess of 800#, has no casters for rolling it and has a counter balanced weight just to assist you in opening the lid of this beast, then I would say no.