The answer to 'air duct greasy' is that dirty, greasy air ducts are often caused by a buildup of dust, dirt, and grease from cooking and other household activities. Symptoms include reduced airflow, musty odors, and visible grime in the ducts. The best solution is to have the air ducts professionally cleaned every 3-5 years to remove this buildup and improve indoor air quality.
While you can try to clean the air ducts yourself using a vacuum with a long hose attachment, it's generally best to hire a professional air duct cleaning service. They have the specialized equipment and expertise to thoroughly clean the entire duct system, including hard-to-reach areas. Attempting DIY duct cleaning without the proper tools can actually push more debris deeper into the system, making the problem worse.