This part was removed by HVAC installer from a fully functioning system. Old system was replaced with new one and was in good working condition. The board was inspected by professional and was in excellent working condition when removed. Purchasing used parts you agree with the statement that sometimes hidden defects or malfunctions may occur during installation or continuous use. Most of the parts require specific knowledge and skills to be installed properly. If you don’t have skills or knowledge, you must ask certified HVAC technician to install.