The answer to 'my air duct is filthy' is that dirty air ducts are a common issue caused by dust, debris, and even mold buildup over time. Symptoms include reduced airflow, decreased energy efficiency, and potential health issues from poor indoor air quality. The best solution is to have your air ducts professionally cleaned every 3-5 years, or more frequently if you have pets, smoke indoors, or live in a dusty environment.
While some homeowners may attempt DIY duct cleaning, it's generally best to hire a professional HVAC technician. They have the specialized equipment and expertise to thoroughly clean your entire duct system without causing any damage. Attempting to clean air ducts yourself can be risky and may not remove all the contaminants.