Furnace filters, often referred to as AC filters, are essential components that keep the air clean while using your air conditioning unit. They also help extend the lifespan of your heating and cooling system by protecting the blower fan from dust mites, dirt, hair, debris, and other pollutants that get sucked in through the return duct. By using a furnace filter, you can also improve the indoor air quality (IAQ) in your home, which may benefit your respiratory health.