7 Signs Your Air Ducts Need Cleaning

These are the ones you can see without any tools.

• Dust puffs from registers when the system kicks on
• Visible dust buildup on register grilles within a week of cleaning
• Black streaking around supply vents
• Dust accumulating quickly on furniture and shelves

Some signs are physiological — they hit your body before they hit your eyes.

• Allergies worse indoors than outdoors
• Stuffy mornings that clear up once you leave the house
• Musty smell when the AC or furnace turns on

Any two of these together is enough to justify a cleaning. Three or more, and you're overdue.