A device and method for air purification used in cooling, heating and air ventilation systems. The device has at least one UV light source positioned on an inside portion of a movable access panel so that it moves with the access panel from a first position where the UV source directs UV light towards the inside of the system to purify the air stream inside and to remove contaminants from the surfaces inside the system, to a second position where the UV source directs UV light towards the space surrounding the system so that it purifies the air in the room where the system is mounted.