About The Author: Travis Baugh is a Digital Brand Marketing Manager for Bryant, where he creates clear, helpful content to guide homeowners through heating, cooling, and indoor air quality decisions. His goal is to empower readers with the knowledge they need to choose the right comfort solutions for their home—confidently and comfortably.
Mold In Air Conditioner Troubleshooting Guide
By Travis Baugh
To address mold in an air conditioner, turn off the system immediately to prevent spreading spores throughout your home. Inspect the air filter, drain line, and evaporator coils for moisture buildup or blockages. While minor surface mold can sometimes be cleaned, significant internal growth requires professional HVAC service to ensure safe removal and restore optimal air quality.
Discovering mold in your air conditioner can be alarming, but taking decisive action ensures your system delivers the clean, comfortable air you deserve. Knowing how to identify, prevent, and address the issue helps ensure your home stays healthy and your AC continues to run efficiently. Keep reading for a comprehensive guide or reach out to your local Bryant dealer for immediate help.
Common Causes Of Mold In Air Conditioner
Mold growth in air conditioners often results from a combination of moisture, warmth, and organic matter (dust). Understanding these triggers is the first step toward prevention.
1. High Humidity Levels
Mold thrives in humid conditions. Split AC units are designed to remove moisture, but if the system doesn’t drain properly, it creates a damp environment where mold can grow, particularly in the evaporator coils and drain pan.
2. Clogged or Dirty Air Filters
Dirty air filters restrict airflow, causing coils to become excessively cold and leading to condensation buildup. Over time, this moisture encourages mold growth, especially if the filter is clogged with dust and allergens. Learn more about air filter replacement.
3. Clogged Condensate Drain Line
The condensate drain line carries excess moisture away from the unit. If the AC drain line is clogged, moisture backs up, creating the perfect environment for mold. A blocked line can also lead to water pooling inside the unit.
4. Poor Airflow
Restricted airflow from closed vents or malfunctioning fans prevents the central air conditioner from running efficiently. This leads to excess moisture that doesn’t evaporate properly, fostering mold growth.
5. Dirty Evaporator Coils
Evaporator coils can accumulate dirt and grime. When combined with moisture, this creates a breeding ground for mold and mildew. Dirty coils also reduce efficiency and performance. Learn more about how to clean AC coils.
6. Infrequent Maintenance
Neglecting regular AC maintenance allows dust, dirt, and moisture to accumulate on the filter, coils, and condensate pan, making it easier for mold to thrive..
7. Leaky Ductwork
Leaky ducts allow warm, humid air to enter the system. If moisture settles in the cooling coils or other areas, it fosters mold growth within the ductwork.
8. Improperly Sized or Installed Units
An incorrectly sized unit may struggle to balance temperature and humidity. If the unit is too large or too small, it can cause excessive moisture buildup. .Learn more about the importance of professional AC installation and what size air conditioner you need.
9. Standing Water in the Drain Pan
If standing water accumulates in the condensate drain pan due to improper drainage, mold can form. The pan is meant to direct water away, but malfunctions can cause stagnation.
Troubleshooting Mold In Your Air Conditioner
Mike Lea, co-owner of Lea Heating & Air Conditioning in East Dundee, IL, explains what homeowners should do if they encounter mold-related issues in their HVAC system.
“If they see mold on the outdoor unit — which is unusual — that’s generally not a concern,” Lea said. “However, if mold appears on the inside of the evaporator coil, it’s important to have an HVAC professional perform a thorough coil cleaning. The best way to prevent mold growth is to install a UV lamp that consistently shines on the coil.”
Here’s a step-by-step guide your local Bryant dealer will take to troubleshooting mold in your AC:
1. Turn Off the AC
Safety first. Before inspection, the dealer will cut power to the unit to prevent spreading mold spores and allow for safe cleaning.
2. Inspect the Air Filter
A dirty filter traps moisture and dirt—primary fuel for mold. They will check for buildup and replace the filter if necessary. Regular replacement is a simple way to breathe cleaner air.
3. Check the Condensate Drain Line
Your dealer will inspect the line for blockages that cause water backup. They may use a wet/dry vacuum or cleaning solution to clear and disinfect the line.
4. Examine the Evaporator Coils
Dirty coils are susceptible to mold. Your dealer will carefully clean the coils with a professional solution to restore efficiency and hygiene.
5. Inspect the Condensate Pan
If the pan is cracked, rusty, or holding standing water, it becomes a mold hazard. Your dealer will clean or replace the pan to ensure proper drainage.
6. Check for Leaks in the Ductwork
Leaky ducts compromise efficiency and invite humidity. Your dealer will seal cracks or repair damage to keep humid air out of your system.
7. Look for Mold on Other Parts of the AC
They will inspect the blower fan and surrounding areas. If mold is found, they will gently scrub affected components with a mold-killing solution without damaging AC parts.
8. Clean the Unit Thoroughly
After addressing specific issues, they will deep clean the entire unit with a mold-killing solution and dry it thoroughly to prevent regrowth.
9. Check Humidity Levels in Your Home
High indoor humidity fuels mold. Use a dehumidifier to keep levels below 60% is a smart way to protect your home environment.
Dangers Of Mold In Air Conditioner
Mold in your HVAC system is more than a maintenance nuisance; it can impact your health and your system’s longevity.
Health Risks
Mold spores released into the air can lead to poor indoor air quality. Breathing these spores can trigger allergies, asthma, or respiratory conditions.
Spread Of Mold Spores
As your air conditioning systems circulates air, it can spread spores to walls, carpets, and surfaces, leading to widespread contamination.
Reduced System Efficiency
Mold buildup restricts airflow and clogs filters, forcing your system to work harder. This increases energy consumption and cooling bills while accelerating wear and tear.
Foul Odors
Mold creates a musty, unpleasant odor that circulates throughout your home, making your environment uncomfortable. Learn more about AC smells.
Damage to HVAC Components
Left untreated, mold can damage vital components like evaporator coils and blower motors, leading to costly repairs or even AC replacement.
Get Help For Mold In AC From Your Local Bryant Dealer
When you need AC mold removal, trust the experts. Your local Bryant dealer can perform a thorough cleaning and inspection, identifying underlying issues to prevent future growth. Schedule an air conditioning service appointment today to invest in a healthy, comfortable indoor environment.
Mold in Air Conditioner FAQs
Yes, mold in your AC can be harmful, potentially causing allergic reactions, respiratory issues, and worsening conditions like asthma, especially with prolonged exposure.
Mold growth is usually caused by moisture buildup, poor drainage, dirty filters, and high humidity within or around the system.
Common signs include a musty odor, visible mold spots on vents or components, and an increase in allergy-like symptoms when the system runs.
The black stuff in your AC could be mold, especially if it appears fuzzy or slimy and is accompanied by a musty smell. However, it could also be soot, dirt, or mildew, so professional inspection is the best way to confirm.
A mixture of EPA-approved coil cleaner or diluted bleach can kill mold on coils. Always follow manufacturer and safety instructions or have a certified HVAC professional handle the cleaning.
Yes. Mold exposure from an HVAC system can cause allergy symptoms, coughing, or respiratory irritation, especially for sensitive individuals.
No—running a moldy AC can spread spores throughout your home. It’s best to have the system cleaned and sanitized before use.
Turn off the system and contact an HVAC professional to clean and disinfect the coils, drain pan, and ductwork. Avoid running the unit until the mold is safely removed.
Learn More About Air Conditioners
- Understand the value in AC tune ups
- Get help with an AC not working, AC leaking water, or AC not blowing cold air
- Find out how long do AC units last?
- Learn how to clean air conditioners
