Austin "Allergies": Are AC Filters Hiding Spring Mold?

By Franklin Everett Shaw

March 30, 2026

The first breath of spring in Austin, Texas, isn’t always the sweet relief you might expect. For many, it’s a signal of stuffy noses, itchy eyes, and a general feeling of being unwell. While cedar fever gets a lot of the blame, there’s another culprit often lurking unseen: mold in your AC system.

It’s time to stop ignoring the potential mold factory circulating air in your home. This article will arm you with the knowledge to identify, test for, and combat mold in your AC system, specifically focusing on the common springtime offenders in Austin: Alternaria and Cladosporium.

First, let’s talk about why Austin is particularly susceptible to AC mold. The city’s humid subtropical climate provides the perfect breeding ground for mold spores. Combine that with the frequent use of air conditioning, which can create condensation and trap moisture, and you have a recipe for disaster.

So, how do you know if you have mold in your AC? Start by looking for visual signs. Check around the vents, the air filter, and the cooling coils for any discoloration, staining, or visible mold growth. A musty odor emanating from your vents is another strong indicator.

But visual inspections aren’t always enough. Mold can hide in hard-to-reach places. That’s where testing comes in.

Here’s a DIY method for testing your AC filter for mold:

1. Gather your supplies: You’ll need a new, clean AC filter (the same size as your current one), a clear plastic bag, a sterile cotton swab, and a mold testing kit (available at most hardware stores or online – look for kits that specifically test for Alternaria and Cladosporium).
2. Install the new filter: Replace your old AC filter with the new, clean one. Run your AC for at least 24 hours. This will allow the filter to collect any mold spores present in your system.
3. Remove the filter carefully: Turn off your AC. Wearing gloves and a mask (to avoid inhaling any spores), carefully remove the filter and place it inside the clear plastic bag. Seal the bag tightly.
4. Collect a sample: Open the bag slightly and use the sterile cotton swab to gently wipe the surface of the filter, focusing on any areas that appear discolored or dusty.
5. Test the sample: Follow the instructions provided with your mold testing kit. This usually involves placing the swab in a petri dish or vial and waiting a specified amount of time for any mold growth to become visible.
6. Interpret the results: Compare your sample to the control provided in the kit. If you see significant mold growth, it’s a strong indication that you have mold in your AC system.

A common mistake people make is using an old, dusty filter for testing. This will give you inaccurate results. Always use a brand new filter to ensure you’re only testing for mold that’s currently circulating in your system.

Another pitfall is not sealing the bag properly. This can contaminate the sample and lead to false positives. Make sure the bag is airtight before collecting the sample.

Now, let’s talk about what to do if you find mold. First, consider upgrading your AC filter. Standard fiberglass filters are only designed to trap large particles like dust and pollen. They’re not effective at capturing mold spores.

Switching to a MERV 13 filter can make a significant difference. MERV (Minimum Efficiency Reporting Value) ratings indicate the filter’s ability to capture smaller particles. A MERV 13 filter can trap mold spores, bacteria, and even some viruses.

However, be aware that using a high-MERV filter can restrict airflow, especially in older AC systems. Check your AC unit’s manual or consult with an HVAC professional to ensure it can handle a MERV 13 filter.

Another DIY solution is using a specialized air purifier with a HEPA filter. HEPA (High-Efficiency Particulate Air) filters are designed to capture 99.97% of particles 0.3 microns in size, including mold spores. Place the air purifier near your AC vents to help remove mold spores from the air.

But what if these DIY solutions aren’t enough? That’s when it’s time to call in the professionals.

Here are some local Austin resources for professional AC cleaning and mold remediation:

• AC Repair Austin: Offers comprehensive AC cleaning services, including coil cleaning and ductwork inspection.
• Mold Remediation Austin: Specializes in mold removal and remediation services, including air quality testing and mold damage repair.
• Reliable AC & Heat: Provides AC maintenance and repair services, including mold prevention and treatment.

Don’t wait until your allergies are unbearable to take action. Addressing mold in your AC system is crucial for maintaining a healthy indoor environment, especially during Austin’s allergy-prone seasons.

It’s also important to distinguish between mold allergy symptoms and cedar fever. Cedar fever, caused by the pollen of Ashe juniper trees, typically presents with a runny nose, itchy eyes, and fatigue. Mold allergies can cause similar symptoms, but may also include a cough, wheezing, and skin rashes. If you’re unsure what’s causing your symptoms, consult with a doctor or allergist.

Remember, preventing mold growth is always better than treating it. Regularly inspect your AC system for signs of mold, change your filters every 1-3 months, and consider investing in a dehumidifier to reduce moisture levels in your home.

By taking these steps, you can breathe easier and enjoy a healthier home environment in Austin, Texas, even during the peak allergy seasons. Don’t let mold steal your springtime joy. Take control of your indoor air quality and reclaim your comfort.