**Austin's AC: Are "Clean" Ducts Hiding Mold?**

By Franklin Everett Shaw

April 6, 2026

The musty smell hits you the moment you walk in from the Austin heat. You’ve had the ducts cleaned, even paid extra for the antimicrobial treatment. But something still feels…off. Don’t dismiss that feeling. It could be hidden mold, stubbornly clinging to your HVAC system and silently impacting your health.

Austin’s unique climate – hot, humid summers and mild winters – creates a perfect breeding ground for mold, especially in older homes in areas like Hyde Park or Zilker. Homes built before 2000 often have ductwork designs and materials that are particularly susceptible to mold growth.

Here’s how to become a mold detective in your own home, even after a professional cleaning.

First, trust your nose. A persistent musty odor, even a faint one, is a major red flag. It’s not just a general “old house” smell. Think damp earth, decaying leaves, or a locker room that hasn’t been cleaned in a decade. This smell often intensifies when the AC or heater is running.

Next, become a visual inspector. Grab a flashlight and a screwdriver. You’re going to check the most likely hiding spots.

• The Evaporator Coil: This is the holy grail of mold havens. It’s located inside your indoor AC unit. Turn off the power to the unit before you open it. Look for visible mold growth on the coil itself. It often appears as black, green, or white fuzzy patches. Use a small mirror to see hard-to-reach areas.
• The Drain Pan: This pan sits beneath the evaporator coil and collects condensation. A clogged drain line can cause water to overflow, creating a perpetually damp environment. Check for standing water, discoloration, or visible mold. A common mistake is only checking the top of the pan; look underneath as well, as mold can thrive there unseen.
• Ductwork Connections: Where duct sections connect, there are often small gaps or leaks. These are prime spots for condensation and mold growth. Pay special attention to connections in unconditioned spaces like attics or crawl spaces. Use your flashlight to inspect the seams carefully. Look for staining or discoloration around the joints.
• Air Vents: Remove the vent covers and shine your flashlight into the ductwork. Look for dust buildup, which can trap moisture and provide a food source for mold. Also, check the vent covers themselves for mold growth, especially on the back side.
• The Air Handler Unit: This unit houses the blower fan and other critical components. Check for any signs of water damage or mold growth inside the unit. Pay particular attention to the insulation lining the inside of the unit, as it can easily harbor mold.

Specific Challenges in Austin Homes:

• Limestone Foundations: Many older homes in Austin have limestone foundations, which can wick moisture from the ground. This moisture can then migrate into the ductwork, creating a favorable environment for mold growth.
• Attic Ventilation: Poor attic ventilation is a common problem in Austin homes. This can lead to excessive heat and humidity in the attic, which can then transfer to the ductwork. Ensure your attic vents are clear and functioning properly.
• Improperly Sealed Ductwork: Over time, ductwork can become damaged or improperly sealed. This allows outside air and moisture to enter the ductwork, creating a breeding ground for mold. Regularly inspect your ductwork for any signs of damage or leaks.

What to do if you find mold:

• Document Everything: Take photos and videos of the mold growth. This will be helpful when you contact a mold remediation specialist.
• Don’t Disturb the Mold: Avoid touching or disturbing the mold, as this can release spores into the air.
• Contact a Qualified Mold Remediation Specialist: In Texas, mold remediation companies must be licensed by the Texas Department of Licensing and Regulations (TDLR). Look for a company with experience in HVAC mold remediation in the Austin area.
• Consider an Independent Mold Assessment: Before hiring a remediation company, consider hiring an independent mold assessor to evaluate the extent of the mold growth and develop a remediation plan. This can help ensure that the remediation is done properly and that you’re not overcharged.

Local Austin-Area Mold Remediation Resources:

• Texas Department of Licensing and Regulations (TDLR): You can use the TDLR website to verify the license of a mold remediation company.
• Better Business Bureau (BBB): Check the BBB website for reviews and ratings of mold remediation companies in Austin.
• Local Austin Home Inspector Associations: These associations can provide referrals to qualified mold assessors and remediation specialists.

Common Mistakes and Pitfalls:

• Ignoring the Problem: Mold problems don’t go away on their own. In fact, they tend to get worse over time.
• DIY Remediation: Unless the mold growth is very small and contained, it’s best to leave remediation to the professionals. Improper remediation can actually make the problem worse.
• Choosing the Cheapest Option: When it comes to mold remediation, you get what you pay for. Don’t choose a company solely based on price. Look for a company with experience, a good reputation, and proper licensing.
• Failing to Address the Underlying Cause: Mold growth is often a symptom of a larger problem, such as a leaky roof or poor ventilation. If you don’t address the underlying cause, the mold will likely return.

Actionable Insights:

• Schedule regular HVAC inspections: Have your HVAC system inspected by a qualified technician at least once a year.
• Change your air filters regularly: This will help prevent dust and debris from building up in your ductwork.
• Ensure proper ventilation: Make sure your attic and crawl spaces are properly ventilated.
• Address any water leaks promptly: Repair any leaks in your roof, plumbing, or foundation as soon as possible.
• Consider a dehumidifier: If you live in a particularly humid area of Austin, consider using a dehumidifier to reduce moisture levels in your home.

Protecting your indoor air quality is crucial for your health and well-being. By taking these steps, you can proactively identify and address potential mold problems in your HVAC system, ensuring a healthier home environment for you and your family in Austin, Texas. Don’t let hidden mold compromise your health and home. Take action today.