Home » Air Conditioning » How to Remove Musty Smell From Air Conditioner

Does your air conditioner smell musty lately, like a damp basement? If so, don’t feel embarrassed – it happens to the best of us! The bigger question is, do you want to know how to remove musty smell from air conditioner?

Bad AC odors can trigger discomfort in many homeowners, even making them feel sick on a few occasions. This is why it’s important to know how to remove musty smell from air conditioner.

Through the guide we created below, you’ll be able to eliminate those unpleasant odors coming off your air conditioning unit. By following our steps, we guarantee that you’ll enjoy fresh-smelling cool air again in no time.

Common Causes of Musty Smells in an HVAC System

Before we discuss the steps, let’s talk abo

Bad odors in your home’s air conditioning system are quite a common issue to deal with. So while it can feel unpleasant and embarrassing to have, it’s not exactly a difficult or expensive issue. In fact, figuring out what’s causing that musty smell odor can help you eradicate it for good.

So before we discuss how to remove musty smell from air conditioner, let’s talk about what’s causing such health hazards. Below are some of the most common causes of musty HVAC odors, and how you can fix it.

Mold Growth

Mold, mildew, and other parasites in an HVAC system can cause musty smells and can be fixed by cleaning and treating the affected areas. A professional should inspect the ductwork, evaporator coils, and other components to locate and remove mold. Improving ventilation and ensuring proper moisture control in the building can also prevent mold outbreaks. Once the mold is removed, the system should be regularly maintained to prevent future mold and mildew growth.

Dirty Air Filters

Dirty air filters can cause a musty smell in an HVAC unit as it can trap dust, dirt, and other airborne particles that can promote the growth of mold and bacteria. It can also cause your unit to not cool properly. To fix this, your AC’s air filter should be regularly checked and replaced when dirty. This is a simple and effective way to improve indoor air quality and eliminate musty smells. It is recommended to check the air filter every month and replace them every 3 to 6 months (or as needed).

Stagnant Water in the System

Stagnant water inside the AC unit can lead to foul odors as it can promote the growth of mold and mildew. The water can accumulate in the unit due to clogged drain lines or poor condensate management. To fix this, the drain lines should be checked for blockages and cleaned if necessary. A professional should also check the condensate pan, drip pan, and drain pan to ensure proper drainage. Proper maintenance of the unit can also prevent stagnant water and foul smells.

Lack of Proper Maintenance or Cleaning

Failing to properly clean and take care of your air conditioning unit is a surefire way to ensure your smells musty and icky. Aside from the general unpleasantness of it all, it can create the ideal environment for mold and mildew growth as well. To fix this, proper maintenance and cleaning of the indoor unit is necessary. This includes cleaning or replacing dirty air filters, cleaning the condenser coil and drain line, and checking for mold or other issues.

Improper Ventilation

Poor ventilation won’t just make sure your air conditioner smells musty all year long. It will also produce excess moisture and boost humidity levels in your home. To fix this, you need to make sure adequate airflow circulates throughout your unit and home. Try installing exhaust fans or vents in the rooms that are prone to high humidity. You could also ask a professional to check for any leaks in the ductwork (more on this in a below), and seal them if necessary. Regular maintenance of the unit can also prevent improper ventilation and bad smells.

Leaks in the Ductwork

Another reason why your AC unit has a musty smell coming from it is probably due to leaks, cracks, or any other forms of damage in its ductworks. This is because they moist air to enter the air ducts, creating the perfect breeding ground for mold, mildew, and bacteria. To fix this, an HVAC technician should check for any leaks in the ductwork, seal them and properly insulate the air ducts to prevent condensation. It is also important to regularly maintain the HVAC system and inspect the ducts for any signs of leaks or mold growth. Addressing leaks in the ductwork promptly can prevent musty smells and improve indoor air quality.

Pests or Animals in the Ducts

At the same time, you should watch out for any pests or animals inside the ducts. Unchecked, they can cause musty smells in your HVAC system as they can leave droppings, urine and other debris which can promote the growth of mold and bacteria. Again, have the professional inspect the ductwork for any signs of critters. Once they’re removed, seal off any holes or gaps in the ducts or in the building that may allow them to re-enter.

Debris Buildup in the System

Letting dust, dirt, and debris accumulate in an AC system will definitely cause musty odors. Unchecked, it can block your ducts, coils and other internal components of the unit over time. To fix this, regular cleaning and maintenance of the system is necessary. This includes cleaning or replacing the air filter, cleaning the evaporator coil and drip tray, and inspecting the air duct, condensate line, drain pan, and what-not.

Clogged or Blocked Drain Lines

Clogged or blocked drain lines can cause musty odors in an AC system as it can lead to stagnant water which can promote mold and bacteria growth. the drain line can become clogged with debris such as dust, dirt and other particles. To fix this, a professional should check the drain line for blockages and clean them if necessary. Additionally, regular maintenance of the system can prevent clogs and musty odors. It is also recommended to check the drain lines every month and clear any blockages as soon as they are noticed.

Bear in mind that not all musty or mildew smell are coming from the air conditioning system itself. Some can be caused by other factors such as outdoor humidity, the presence of swamps, rivers, and other bodies of water, mold spores in the garden, and more. Thus, it’s best to have an AC professional come and inspect your unit and the surrounding areas to determine the source of that persistent musty smell.

10 Steps to Eliminate Musty Smells From Your AC Unit

Now that you know what’s causing that musty smell, you’re probably wondering what steps to take in order to get rid of them for good. So to make your life easier, we’ve put together ten simple and effective steps that will help you eliminate those musty odors that are currently plaguing your air conditioner.

  1. Turn off the air conditioner and unplug it.
  2. Clean or replace the air filter.
  3. Locate and clean the evaporator coils with a soft brush.
  4. Clean the condensate drain line and pan.
  5. Check for mold and mildew growth and get rid of it if present.
  6. Pour disinfectants or a cleaning solution in a spray bottle and apply it on all surfaces.
  7. Run the air conditioner on the fan setting to circulate fresh air.
  8. Place an odor-absorbing product, such as baking soda, near the unit.
  9. Check and clean the ductwork if necessary.
  10. Have an HVAC expert inspect and service the air conditioner if the musty smell persists.

It is important to note that depending on certain factors such as the severity of the musty smell and the reason it’s there in the first place, some of the steps above may be more effective than others. So take the 10 steps above as a general guide for removing smelly odors from air conditioners. Again, if symptoms persist, best leave it to a professional.

Learn How to Remove Musty Smells From Air Conditioner

No one wants their home to smell musty, but sometimes it’s unavoidable. So as soon as you notice that your AC smells musty, take action and figure out the source of the problem. Learn how to remove musty smell from air conditioner. And watch out for the causes mentioned above. Once you find out the root of the problem, proceed with the steps we listed above.



How do I get rid of the musty smell in my air conditioner?

Regular cleaning and maintenance of the AC unit and filters can help eliminate musty odors. Vacuum the interior, replace the filters, and use an AC cleaning solution to disinfect the unit. Consider hiring a professional to inspect and clean your AC system if the odor persists.

Why does my air conditioner smell musty?

Musty odor in an air conditioner is usually caused by mold or bacteria growth in the unit. This can happen due to condensation and stagnant water inside the AC, or from dirty filters that trap moisture. To prevent the growth of mold, maintain clean filters, drain the condensation pan, and keep the unit running regularly to avoid stagnant water buildup.