If ac units are not properly insulated, ac unit condensation can form on ac air supply outlets by way of metal ac ductwork. Moisture formation is the primary cause of mold growth in ac units. Mold spores are present everywhere and they enter ac units through openings around ventilation louvers or diffusers, especially during periods of high humidity when replenishing indoor moisture becomes difficult for each ac vent to maintain. Moisture buildup inside ac metal ducts can be prevented by way of insulation which will minimize cold air loss from metal ac vents throughout the house.