If the fridge temps get too cold near the lower section where the water reservoir is located, it will freeze the tank up. This will likely be accompanied by frozen veggies in the crisper drawers, maybe not. To see if it is merely a frozen tank, remove the lower drawers and heat the plastic tank in back slowly and evenly with a hair dryer or about 10 minutes. If it was frozen, the water should now dispense. If not, replace the dual water valve in back and change the incoming water filter if so equipped.