Yes, it's a good idea. The EPA recommends:"in the winter, be sure to insulate room air conditioners from the outside with a tight-fitting A/C unit cover." Frost King has a full selection of AC covers to keep both your window AC units and central AC units covered throughout winter. See where to buy Frost King's cost-saving AC covers. Once your AC is covered for winter, add more protection from the cold with Frost King's window seal products.