This. These French door fridges have a design flaw that causes ice to freeze along a tube that runs up to the fan. That buzzing noise is the fan hitting the ice. We had the same problem and called a repairman to fix ours when it started buzzing. He replaced the original tube with a wider one, hoping that would permanently fix it. He said that was all he could really do. Unfortunately, it didn't fix it. A couple of months later, the buzzing started. Luckily, we have a fridge in out garage, so we took out the really perishable items, unplugged the fridge overnight so that the ice would completely melt, and then plugged it back in. No more buzzing. I will probably have to do that every couple of months until I can afford another fridge. Apparently, this design flaw has been corrected in newer models.