AC & Air Duct Mold Removal in Houston, TX

Where AC mold starts in Houston homes

Houston's long, humid cooling season keeps the system wet for months. In many homes the air handler and much of the ductwork sit in a hot attic, where cold ducts pull moisture from the air. Common sources:

• A clogged condensate line or a rusted, standing-water drain pan under the air handler
• Duct runs or boots that sweat because insulation is torn or missing
• Supply registers that drip in summer and grow spots on the grille and nearby ceiling
• An oversized unit that cools fast but removes little moisture, leaving indoor humidity high
• Duct lines or an air handler that took water during a flood

What to do before anyone comes out

If you suspect the system is contaminated, EPA advises not running it, because it can spread mold through the house. In August heat that is hard, so ask about portable cooling while the work is planned. Check the drain line, keep indoor humidity below 60 percent (30 to 50 percent is better), and don't spray household cleaners into ducts.

How the work is usually scoped

EPA's guidance on duct cleaning makes a useful point: if the moisture problem is not corrected, mold will come back, however well the ducts were cleaned. Expect the assessor to look at drainage, insulation and humidity, not just the visible spots. An HVAC contractor may need to repair the equipment itself.

Texas rules and two companies

Anyone hired to assess or remove mold needs a TDLR license, and Texas law says the company that assesses cannot also remediate on the same project. The consultant writes a protocol before work, the remediator follows its own work plan, and a post-remediation assessment checks clearance before you receive a Certificate of Mold Damage Remediation. You can check both companies on TDLR's license search.

Cost

National ranges (HomeGuide, 2026) put mold work on an HVAC system or ducts at $2,000 to $10,000; Angi national figures add about $50 to $75 to an air test for an HVAC sample. Duct length, attic access, how much flex duct is replaced and equipment repairs drive the price, plus the assessor's fee.