It's time to change your furnace filter! Remember, most air filters need to be changed at least once every 30 days. They need to be changed more often during summer and winter months when your system is running almost constantly.
Aside from being good for your unit, changing your filter regularly is good for your health. Air filters are designed to trap dust, mold, pollen, and other indoor air pollutants. These pollutants can aggravate allergies or asthma.