How Do I Know If My HVAC System Spread Mold Through My House?

Mold spread through an HVAC system usually leaves visible clues. Check the air registers, the grilles on walls or ceilings, for black or green speckling. Look at the surfaces right around each vent, too, because mold spores that blow out can settle and grow on nearby drywall or carpet.

Mold often grows in the places you cannot see. The evaporator coil inside the indoor unit collects moisture and dust, which is a perfect spot for mold. The drain pan and the condensate drain line can also harbor mold if they stay damp or clogged. Supply ducts, the ones that blow air into rooms, can develop mold on their inner surfaces.

Return ducts, which pull air back to the unit, can grow mold too, especially if they pass through a humid crawlspace or attic. Insulation lining inside ducts is another common hiding place. A water damage inspection can help you find these hidden growth areas, since a pro can look inside the system and ductwork with the right tools.

If you see mold on more than one vent, smell a musty odor, or have health symptoms, it is wise to call in professionals. Mold inside ductwork is not a DIY cleanup job. The pros have equipment to inspect the entire system, identify the moisture source, and clean or remove contaminated materials safely.

You should also involve the pros if the mold came after a water leak, like a burst pipe or an AC drain line overflow. Damp duct insulation and drywall can harbor mold even after the visible water is gone. A water damage inspection can map out what needs attention, and related services like drywall repair or flooring removal may be part of the solution.

• Turn off the HVAC system to stop spreading spores
• Check all vents and nearby surfaces for dark spots
• Look for a musty smell that worsens when the system runs
• Inspect the drain pan and condensate line for standing water
• See a doctor if you feel unwell
• Contact the pros for an inspection if you find mold