The answer to 'my air duct cleaning is filthy' is that your air ducts likely need professional cleaning. Dust, dirt, and debris can accumulate in air ducts over time, reducing air flow and indoor air quality. Common causes include pet dander, construction dust, and general household dirt and grime.
Signs your air ducts need cleaning include poor airflow, increased dust/allergens, and visible dirt buildup. Regularly scheduled professional air duct cleaning (every 3-5 years) is recommended to maintain healthy indoor air and HVAC system efficiency. While some light DIY cleaning is possible, it's best to hire a licensed HVAC technician for a thorough, professional air duct cleaning.