Oh, I agree that under normal circumstances, the condenser coil being dirty wouldn't cause ice buildup, but with how incredibly overengineered Samsung makes their brown-goods, I wouldn't put it past them to have some sort of circuit that would cause frost buildup in the freezer. They really need to stick with phones, tablets, TV's and wearables, or dramatically dumb-down the controls for their refrigerators, washers and dryers, and other appliances. But yea, my bet is the defrost board...