I HAVE GOT A SAMSUNG AMERICAN STYLE FRIDGE FREZZER RS21DCSV & IM HAVING PROBLEMS WITH MY FRIDGE FREZZING UP WITH LOTS OF BUILD UP OF ICE RIGHT AT THE BACK OF MY FRIDGE. I HAVE DEFROSTED THE FRIDGE ONCE BUT HAD THE SAME PROBLEM ONCE THIS WAS DONE. CAN U PLEASE HELP ME ANSWER THIS QUESTION. THANK YOU.