DIAGNOSIS The defrost drain is clogged. During the defrost cycle, melted ice should drain through a hole in the back of the freezer compartment into a drain pan below. Food debris or ice blocks this hole.
FIX Unplug the unit. Remove all food and the crisper drawers. Locate the small drain hole at the back center of the freezer compartment. Use a turkey baster filled with warm water to gently flush the hole. You can also use a pipe cleaner or soft plastic tubing to clear debris. Do not use sharp objects.
IF THAT DIDN'T WORK The drain tube itself, which runs from that hole to the pan under the fridge, may be kinked or frozen solid. You may need to access the back panel to check the tube's path.
HEADS UP Prevent future clogs by ensuring food packaging isn't touching the back wall where the evaporator is. Condensation from packages can freeze and block the drain.