I've had this problem where the unit behind the back wall freezes up causing water/ice to form in the bottom shelf or developing ice that interrupts the fan. We have called a repair person out 3 times. His comment each time is this is a common problem with GE refrigerators caused by poor design and essentially not repairable. We are finally convinced the only solution short of buying a new one other than GE or to defrost it every one or two months. Repair guy says Samsung is even worse.