Why Does My AC Smell Musty?

Learn about HVAC & Home Performance in Houston.

Lady next to smelly wall air conditioner

January 26, 2024

AC Maintenance Air Conditioning

You walk into your home and office and notice a musty smell, and after a little investigation, you figure out it’s coming from the air conditioner. A musty smell for an air conditioner is not just an inconvenience, it could signal major issues with the unit and cause health issues. It could be a result of mildew or mold growth, issues with drainage, faulty components, or several other types of issues that can cause an Air conditioning system to smell musty.

A properly functioning Air conditioning unit should not have an unusual or unpleasant smell. If you notice a strange smell from the Air conditioning unit, you should get it inspected by a qualified Air Conditioner technician. If you live in Houston, TX, or other nearby locations, you can contact us at HousePro to have a trained, qualified, and experienced technician repair your AC.

Common Causes Of Musty AC Smells

In some cases, a smelly Air Conditioner only lasts for a day or two after you switch on the Air Conditioning unit for the first time or after several days of not using it. However, if the stale smell does not go away, then there are more serious issues with the AC. If you don’t fix the problem, your AC unit could become a breeding ground for bio-growth.

The first step in fixing this problem is to identify what is causing the musty smell. Understanding the different causes of AC smells musty can help you identify the issue.

In some cases, there could be a combination of reasons for this issue. You may also need to disassemble a few AC unit components to figure out where the musty smell is coming from. If you don’t have the tools or experience to perform an inspection, it is best you allow an Air Conditioner technician to handle the inspection. Here are some of the top causes of musty AC smells:

Dirty or Clogged Air Filters

One of the most common causes of a musty AC smell is a clogged or dirty air filter. Air filters are designed to remove airborne contaminants from the indoor air; however, these contaminants accumulate on the air filter, causing it to become clogged. The good news is that this issue can be fixed by either cleaning or replacing the clogged or dirty air filter. If it’s been several months since you cleaned or replaced the AC air filter, there is a good chance that it could be the issue that is causing the AC to smell musty.

Accumulation of Moisture in The AC System

If your AC unit has accumulated moisture, it could lead to a stale smell. The excessive moisture could be a result of refrigerant leaks, poor insulation, clogged drain lines, lack of ventilation, or several other reasons. Moisture can provide the ideal environment for the growth of mold and mildew.

Improper AC Maintenance

The air conditioner requires regular maintenance services such as cleaning the AC filter, thermostat calibration, checking refrigerant pressure, and clearing the air inlet and outlets of any obstructions. Neglecting proper AC maintenance from a professional HVAC technician can lead to a host of problems, including contaminated evaporator coils, and ductwork leaks which can cause musty smells as one of the problems. It is important to schedule a professional duct cleaning service to prevent the buildup of dust and mold that can create an unpleasant odor in your home. Regular maintenance by a professional HVAC technician can also help keep your air vents and air intake clean and free of debris, ensuring your air conditioner operates efficiently and effectively.

Mold And Mildew Growth in The AC Unit or Ductwork

Mold and mildew can grow in different parts of the AC unit or ductwork. The contaminated air and the dark and damp conditions can promote the growth of mold and mildew, which, if left untreated, can cause a musty smell.

Air Conditioner Fan on the wall outside

Effects Of Musty AC Smells On Indoor Air Quality And Health

If you are wondering whether musty AC smells have an impact on your health and indoor air quality, then the answer is yes. A musty AC smell is a safety hazard to not only those who are sensitive to air quality but to everyone. Poor indoor air quality can lead to allergies, respiratory issues, and several other health concerns.

If someone suffers from asthma, their condition can get worse due to poor indoor quality. It can also lead to headaches and fatigue. The long-term health effects of poor air quality are even more serious as it can cause a variety of severe respiratory conditions.

How To Identify The Source Of The Musty Smell

So now that we understand how important it is to address the issue of a musty AC smell, let us explore the steps to identify the source of the musty smell. You want to start your investigation by checking if the smell is coming from the AC, as there could be other issues with your home or office that can lead to a musty smell.

Once you have identified the AC as the source, you need to dig deeper. Start by looking at the AC components to check if there are signs of moisture or damage such as mold or mildew growth.  Inspect the ductwork for damage and check the AC components for any visible signs of leakage. You also want to check the air inlet and outlet of the AC unit, as any blockage can cause issues with the AC that can lead to strange smells.

Effective Solutions To Eliminate a Musty AC Smell

Replacing Dirty Or Mold-Infested Air Filters

If you are lucky, the musky smell would be a result of a mold-infested air filter, which can be replaced. However, if the issue has spread to other components of the AC, then you would need professional AC service or repairs. You may also need to improve ventilation to reduce humidity levels to help discourage mold growth.

Clear The Air Ducts of Debris

The AC dirty air ducts should have unobstructed airflow. If there are any debris or obstacles in the way of air ducts, they can lead to stagnant air and moisture buildup, which are common causes of musty odors in air conditioners.

Addressing Water Leaks And Excessive Moisture

An effective solution to fix a musty smell is to find and fix any areas that have water leaks or excessive moisture. Common areas for water leaks and moisture include drain lines, drip pans, and refrigerant lines. Small water leaks might be difficult to identify and you may need professional assistance. You can also control excessive moisture by monitoring humidity levels. If you need to reduce the humidity, you can consider installing a dehumidifier device.

Professional AC Cleaning And Maintenance Services Offered By HousePro

The safest and most reliable method to fix musty AC smells is to get a professional AC cleaning and maintenance service from HousePro. We have extensive experience fixing such issues. Our team can also check if any components require repair or replacement service as they can save you from expensive repairs in the future.

Invest In a New Air Conditioner

If nothing works to fix the musty smell issue, you may have to invest in a new air conditioner. This might seem like an expensive option, but it can be more cost-effective in cases where a faulty AC needs regular repairs. If your AC is older than 10 years, then it might have other issues, such as low energy efficiency. While a well-maintained AC can last long, ACs that are more than 10 years old are likely to underperform.

If you are not sure which is the right condition of your property, our HousePro technician can help you make that decision. We understand that buying a new air conditioner is a big investment, so we can offer you our recommendation for the right balance between performance and cost.

Worker Fixing An AC Unit

Tips For Preventing Future Musty AC Smells

The best way to prevent your AC unit from smelling musty is to get regular maintenance service from a professional AC technician. Even if your AC unit is functioning well, you should still stick to the maintenance schedule. Routine AC maintenance can identify issues before they turn into major problems that lead to a musty AC smell.

If you need to replace a part, invest in high-quality products made from reliable manufacturers. The investment in these parts offers value for money as they will last longer and allow the AC to deliver its best performance.

Another way to prevent future musty AC smells is to take prompt action regarding any water leakage or moisture issues. It is a common mistake to delay getting service for small leaks, but if you allow mold or mildew to grow, it can spread quickly.

Additional HVAC Services Provided By HousePro

At HousePro, we offer a full range of HVAC services, including heating and cooling system services such as furnace repair and replacement. Our technicians are also experienced in home performance services such as indoor air quality and energy savings services. Our AC services include repairs, replacement, tune-ups, eliminating musty AC odor, and more.

With over two decades of experience in HVAC services, we have gained a reputation as a reliable and trustworthy HVAC service provider in Houston, TX, and surrounding locations. We can handle all your HVAC needs. To schedule a visit from a technician from HousePro, please contact us.