Warm fridge cold freezer. I had this problem and had to keep manually defrosting the fridge once a week. The auto defrost melts the ice but it does not drain away it freezes in the drip tray and eventually blocks the cold airflow. So UNPLUG the freezer. In the freezer compartment take off the light, undo the back panel take it off. There is a further panel take that off as well, you will need to undo the fan connector. Defrost the freezer completely and see if the water collecting in the tray drains, even if it does get a length of plastic pipe and blow down the drain hole, you will probably have to safely stand on something and use a torch to see it , it is on the left side of the water collector. Worked for me.
Relieved UK, August 2012
