Yesterday our G.E. fridge went into defrost mode. ( I think) There was a noise like a low growl coming from the back just above the condenser. The temp in the freezer/ fridge rose to 36 and 60 degrees respectively. Eventually (several hours later, and much lost food) it went back to it's normal temp of 0 & 37 degrees. This morning it seems normal. We had the main board replaced about 1.5-2 years ago, but at that time the unit wouldn't cool at all. I'm not sure it would be the board again as I've not heard of a board working intermittently. Any thoughts?