We had an almost identical problem and it was caused by the weight of the items in the fridge door. When it was filled it was heavy, and because of this the door contact at the top of the fridge was not being pushed. To check close the door and peel open a bit of the sealing strip to see if the light is on. If this is the problem tape some card at the top of the door to make the switch activate. Good Luck.
Graham
May 2005