Hi! I have had the same problem with my electrolux freezer . The engineer in my local independent shop told me to switch off the f/freezer and empty it out and leave it for three days with doors open . The reason for this is that frost builds up in the back of the Freezer causing a blockage to the air flow from the fan , I have done this and my f/freezer is working fine ( IT is eleven years old ) hope this helps
Regards Vince, June 2009