If you've ever noticed a foul odor while running your Central Air conditioner this might indicate mold build up on the coil fins. These contaminants will be eliminated with your UV light as the air cycles through your system.
UV light attachments kill contaminants through the use of UV-C light, otherwise known as germicidal UV light, frequently used in hospitals. The light disrupts contaminants' DNA, preventing them from reproducing, effectively killing them, or inactivating them.
We recommend that you leave your furnace/ac system in fan mode to continue cycling the air through your system. Many programmable thermostats have a setting for this. Mold and other contaminants don't stop growing when your system is off, to ensure your furnace and ac system is clean you should have the air continuously recycled. Also having the light turn on and off will shorten the life of the light. The light should be replaced annually and can be replaced during annual preventative maintenance.
UV light will not damage any internal parts in your system, but it should not be looked at directly by the human eye. Looking directly at the light can cause a sunburn on your eyes. The UV light is only harmful to contaminants like germs, pollutants, viruses, and other microbiological material, it is safe to expose children and pets to it.