Why Does My Air Conditioner Smell Musty (How to Fix It)

There is nothing better than refreshing AC on a hot summer day.

As the weather gets warmer, many of us begin to rely on our air conditioners to keep us cool and comfortable. However, while a well-functioning AC unit is critical to enjoying your summer, it’s also important to make sure that your unit is healthy. A healthy AC unit will not only provide you with optimal cooling power but will also help to improve your indoor air quality and extend the life of your unit. If you do not do so, it can result in your air conditioner not functioning properly, even to the extent of making your air conditioner smell musty!

Reasons why your air conditioner smells musty and ways for how to get rid of this include:

  • It’s not getting enough air circulation & filter needs to be changed
  • AC filter is dirty and needs to be changed
  • AC coils are dirty and need to be cleaned 
  • Mold/Mildew
  • Clogged Drain line and it needs to be cleared
  • AC unit is old and needs to be replaced


There are a few simple things you can do to keep your HVAC unit healthy this summer. First, be sure to change your air filter regularly. A dirty air filter can impede airflow and cause your unit to work harder than necessary, which can lead to premature wear and tear.

Second, keep your AC unit free of debris by regularly cleaning the outside coils. Debris can build up on the coils and prevent heat from being properly released, which can cause your unit to overheat.

Finally, be sure to schedule regular maintenance appointments with a qualified HVAC technician. Regular maintenance will help to ensure that your unit is operating at peak efficiency and catch any potential problems before they cause major damage.


why air conditioner smell musty


Why does my air conditioner smell musty when I run it?

If you have just started to use your air conditioner now that the heat has started to intensify in your area, you may notice a smell in the air that isn’t quite pleasant. If that is the case, then you want to check on a few things as soon as possible.

 Your air conditioner smells musty because it may not be getting enough air circulation.

There are a few things that contribute to air circulation in an AC unit. The first is the blower, which is responsible for circulating air within the unit. The second is the condenser, which helps to cool and dehumidify the air. Finally, the evaporator helps to circulate the cooled and dehumidified air back into the room. All of these components work together to ensure that air is circulated properly in an AC unit.

There are a few things you can do to make sure the air in your AC unit is circulating properly. First, check the air filter and make sure it isn’t clogged. Second, open all the vents in the room (if possible) to allow for better circulation. Finally, consider using a fan to help circulate the air.

Your AC smells musty because the filter is dirty and needs to be replaced.

If your air conditioner isn’t getting enough air circulation, it could be a sign that the filter is dirty. A dirty filter can restrict airflow, causing your AC to work harder than necessary to cool your home. Check the filter and clean or replace it if necessary. If the problem persists, it may be due to a blockage in the AC unit itself. Check for any obstructions and clear them away if possible. If the issue continues, you may need to call a professional AC repair technician for assistance.


why does air conditioner smell musty


Your air conditioner’s coils are dirty and need to be cleaned.

The coil in your AC unit is responsible for transferring heat from the inside of your home to the outside. This process is known as refrigeration, and it is how your AC unit is able to keep your home cool during hot weather. The coil consists of a series of coils that are filled with a refrigerant. As the refrigerant evaporates, it absorbs heat from the air inside your home. The refrigerant then travels to the outside of your home, where it releases the heat into the air.

In order to keep your AC unit running efficiently, it is important to keep the coil clean. A dirty coil can reduce the efficiency of your AC unit by as much as 30%. As the coils become clogged with dirt and dust, they are not able to transfer heat as effectively. This results in your AC unit having to work harder to cool your home, which leads to higher energy bills.

There are a few simple things that you can do to keep your AC unit’s coil clean. First, make sure that you change the filter on your AC unit regularly. A dirty filter will cause dirt and dust to build up on the coil more quickly. Second, if you have pets, make sure that they are not allowed to sleep on or near the AC unit. The fur from your pets can clog the coils and reduce their efficiency. Finally, if you live in an area with a lot of dust, you may want to consider investing in a Coil Cleaning Kit.

Your AC smells musty because there is mold or mildew growing inside of it.

Mold and mildew can build up in your air conditioner for a number of reasons. Most often, it is due to condensation from the cooling coils. This happens when the air conditioner is not able to properly drain the water that has condensed on the coils. The water then sits in the unit and provides a perfect environment for mold and mildew to grow.

Another common cause of mold and mildew in air conditioners is leaking. If there is any type of leak in the unit, whether it is a refrigerant leak or a water leak, this can also create an environment where mold and mildew can grow.

In some cases, mold and mildew can also be caused by the build-up of dirt and dust on the coils. This can happen if the air filter is not changed regularly or if the air conditioner is not cleaned on a regular basis. When the coils are covered in dirt and dust, they are unable to properly cool the air, which can cause condensation to occur. This condensation can then lead to mold and mildew growth.

If you do find mold or mildew in your air conditioner, there are a few things that you can do to remove it. One option is to use a commercial mold and mildew remover. These products are designed to kill mold and mildew on contact and can be found at most hardware stores.

Another option is to clean the coils of your air conditioner with a bleach solution. This will kill any mold or mildew that is growing on the coils. Be sure to follow the manufacturer’s instructions carefully when using bleach, as too much can damage the coils. Once the coils are clean, you can then vacuum them to remove any remaining mold or mildew.

If you are still having problems with mold or mildew after taking these steps, you may need to replace the air conditioner.

Your AC smells musty because the drain line is clogged and needs to be cleared.

One of the most important things you can do to keep your air conditioner running properly is to clean the drain line. A clogged drain line can cause your air conditioner to leak water, which can damage your home and lead to costly repairs.

Fortunately, cleaning the drain line is a relatively easy task that you can do yourself. You will need a few simple tools and supplies, including a wet/dry vac, a funnel, and some bleach or vinegar.

Start by unplugging your air conditioner from the power outlet. Then, remove the access panel so that you can access the drain line. Locate the drain line and use the wet/dry vac to suction any water or debris that may be inside.

Once the line is clear, mix a solution of bleach or vinegar and water and pour it into the drain line. Use the funnel to help guide the mixture into the line. Then, replace the access panel and plug your air conditioner back in.

Let the unit run for a few minutes to allow the solution to work its way through the system. Then, turn off the power and use the wet/dry vac to suction any remaining solution from the drain line. Finally, replace the access panel and screw it into place.

Your air conditioner smells musty because the unit itself is old and needs to be replaced.

If your AC unit is more than 10 years old, it may be time to start thinking about replacing it. Here are a few things to look for that may indicate your unit is too old:

  • Rising Energy Bills – If your energy bills have been gradually increasing each year, it could be due to inefficiency from an old AC unit.
  • Frequent Repairs – Older units tend to break down more often and require more repairs. If you’re constantly having to call a repairman, it may be time for a new unit.
  • Uncomfortable Indoors – An old AC unit may no longer be able to effectively cool your home, leaving you feeling hot and uncomfortable indoors.


man gets rid of air conditioner smell musty


Don’t let that musty smell linger.

The bottom line is that you need to keep your air conditioner healthy in order to have a comfortable home. A musty smell coming from your AC unit could be a sign that it is time to replace the unit. Luckily, there are a few things you can do to clean the unit and get rid of the musty smell. If these steps don’t work and you’re still wondering why does my air conditioner smell musty, it may be time for a new AC unit.