Just like our parents old fridges; it needs defrosting from time to time; the high humidity can cause ice to form aroung the cooling element and eventually this jams up the fan with a solid block of ice which prevents the cold air circulating around the fridge.
Turn the fridge off and leave the fridge door open, it takes at least 24h to defrost so you may want to transfer the freezer content first or you could do it in stages and turn the fridge back on (low) overnight (shut the door again).
Should do the trick and its free!
white Knight
August 2007