Houston Humidifiers: AC Mold Making You Sick?

By Franklin Everett Shaw

August 9, 2025

The air in Houston feels different. It’s thick, heavy, and clings to you like a damp towel. This humidity, while sometimes refreshing, is a breeding ground for a silent, unwelcome guest in many Houston homes: mold in your AC system. Ignoring this problem isn’t just about a musty smell; it’s about your health and the longevity of your AC unit.

Houston’s climate creates a perfect storm for mold growth. High humidity, combined with the dark, enclosed spaces of AC units, provides an ideal environment. Mold spores are everywhere, and they thrive on the condensation that naturally forms within your AC system as it cools the air.

So, what exactly are you dealing with? Common mold types in Houston homes include Cladosporium, Aspergillus, and Penicillium. These molds can trigger allergic reactions, asthma, and other respiratory problems. Black mold, or Stachybotrys chartarum, while less common, is a more serious concern due to its potential to produce mycotoxins.

Identifying mold early is crucial. Look for these telltale signs:

• A musty or earthy odor coming from your vents.
• Visible mold growth on or around your AC unit, particularly in drip pans or on coils.
• Increased allergy symptoms, such as sneezing, coughing, or itchy eyes, when the AC is running.
• Dark spots or discoloration on walls or ceilings near vents.

If you spot any of these signs, don’t panic. You can take action.

For minor mold issues, DIY cleaning can be effective. First, always turn off the AC unit at the breaker to avoid electrical shock. Then, gather your supplies:

• EPA-approved mold cleaner (look for products containing quaternary ammonium compounds).
• A stiff brush or scrub pad.
• A vacuum with a HEPA filter.
• Protective gear: gloves, mask, and eye protection.

Clean the visible mold growth with the cleaner and brush. Be thorough, but avoid damaging the AC components. Vacuum up any loose debris with the HEPA filter vacuum.

A common mistake is using bleach. While bleach can kill surface mold, it doesn’t penetrate porous materials and can actually worsen the problem by providing moisture. Stick to EPA-approved mold cleaners.

Another pitfall is neglecting the drip pan. This is a prime breeding ground for mold. Clean it regularly with a mixture of water and vinegar or a commercial AC coil cleaner.

However, DIY cleaning isn’t always enough. If the mold growth is extensive, or if you suspect black mold, it’s time to call in the professionals.

Several Houston-area HVAC companies specialize in mold removal. Companies like One Hour Air Conditioning & Heating of Houston and Reliant Air Conditioning offer mold remediation services. They have the equipment and expertise to safely and effectively remove mold from your AC system and prevent its return.

When choosing a professional, ask about their mold remediation process. A reputable company will:

• Conduct a thorough inspection to identify the source and extent of the mold growth.
• Use specialized equipment, such as air scrubbers and HEPA vacuums, to contain and remove mold spores.
• Apply antimicrobial treatments to prevent future growth.
• Offer recommendations for improving ventilation and reducing humidity.

Be wary of companies that offer suspiciously low prices or use harsh chemicals that could damage your AC unit or harm your health.

Preventing mold growth is the best strategy. Here are some preventative measures you can take:

• Regular AC maintenance: Schedule annual tune-ups with a qualified HVAC technician. They can clean the coils, check for leaks, and ensure proper drainage.
• Control humidity: Use a dehumidifier, especially during the humid summer months. Aim for a humidity level between 30% and 50%.
• Improve ventilation: Ensure proper airflow throughout your home. Open windows and doors when possible, and use exhaust fans in bathrooms and kitchens.
• Change air filters regularly: Dirty air filters restrict airflow and can contribute to mold growth. Change them every 1-3 months, or more often if you have pets or allergies.
• Consider UV lights: Installing a UV light in your AC system can kill mold spores and other microorganisms.

One often overlooked area is the ductwork. Leaky or poorly insulated ducts can create condensation and promote mold growth. Have your ductwork inspected and sealed if necessary.

Living in Houston means dealing with humidity. But it doesn’t mean you have to live with mold in your AC system. By taking proactive steps to identify, clean, and prevent mold growth, you can maintain healthy indoor air quality and protect your health and your investment in your AC unit. Don’t let mold win; take control of your indoor environment.