The purpose of the Ultra Violet light is to eliminate Mold and Bacteria from the surface of your air conditioning coild before air blows over the coil and move sthe mold and bacteria into your home. Mold and Bacteria thrive in dark / cool locations but cannot survive under UV light. Though not a required accessory for most installations, those with health and / or allergy issues should speak to your Dyand Estimator about the potential benefits of putting a UV light in your system.
Carrier UV lights are available in either single or double bulb configurations.
Annual bulb changes are reccomended as while the light may still be appear to be bright, the UV spectrum wears over time and is no longer effective