The drain is stopped up. The drain is located in the bottom of the freezer under the evaporator. You may have to remove the cover off the back of the freezer or you may not depending on the model. In any case you must remove the ice in the bottom of the freezer and all the ice over the drain hole. Then clean the drain by forcing hot water down it until water flows down freely. I always use a turkey baser but you can use any squirt bottle. Refrigerator repair guide