just had the same problem with mine if you take the back pannal off the freezer(inside) you will find a fan when you open and close the fridge door this fan comes on to remove the warm air etc.now this is worked by the pannel with the lcd on it that packs up over time (some kind of relay)so just take a wire from the fan(the one going into the white plug)and fix it to a perm live.i did mine by placing a wire down the drain pipe and conecting it to the compressor's live point.this means the fan runs all the time.did mine over six months ago and its still going.
carl watson., December 2008