FJC�s Air Conditioning Dyes mix with the oil and refrigerant and circulate throughout the A/C system. At the area of a leak, a small amount of dye will escape and stain the area with dye, exposing the leak. UV/Fluorescent dyes allow the operator to see this with the aid of the UV lamp and enhancing glasses, while red dye is evident to the naked eye. A repair can then be conducted to the affected area.