Possibly the fridge side defrost heater, The part comes with the evaporator coils, which is not needed, about £70. Happened on mine, Samsung extended the warranty to 5 yrs on some of these, because of problems, they have a modification, which goes on the pcb in the back to stop it tripping, I got my money back, So worth asking Samsung first, get it fixed for free, plus all the modifications that go with it, which with labour etc, would cost more than the unit. No they did not tell anyone, that was why I fixed mine myself, Then found out about the warranty extension
SD, September 2011