How to fix a musty air conditioner

In order to fix a musty air conditioner, you need to clean your evaporator coils, vents and ducts, and drainage pan to get rid of mould.

Mould, mildew, and other bacteria need water, oxygen and a food-source to grow. This makes air conditioners the perfect breeding ground for these organisms.

When mould and other organisms grow on the evaporator coils, ducts and vents, or even the drain pans of your air conditioner, this can cause a musty smell. Fortunately, this can be fixed by cleaning these components thoroughly.

Mould and air conditioners

The ideal climate for mould, bacteria, and mildew to grow is in high-humidity, shady areas. This is part of what makes air conditioners of all shapes and sizes an ideal space for these organisms to live and thrive in.

In order for this type of fungus to grow in a space, it needs to have moisture, oxygen, and some type of food source, all of which can be present in various places throughout your air conditioning system.

In fact, mould spores can be blown throughout the ductwork and drainage system of your air conditioner, which means that it spreads easily once it has the chance to grow.

How to fix a musty air conditioner

When this mould, mildew, and bacteria starts to build up in varying components of your air conditioner, this can lead to a musty odour.

This smell is often referred to as a dirty sock smell and is quite common in air conditioners when they have not been used for a while or are not cleaned regularly.

Fortunately, there are various ways that you can fix this. There are several reasons why excess moisture may be accumulating within different parts of your air conditioner, such as frozen evaporator coils and ducts or vents or drainage issues.

This excess of moisture creates the perfect breeding ground for mould, mildew, and bacteria, which could be what is causing the musty smell in your air conditioner.

Therefore, letting the coils thaw and thoroughly cleaning the vents and ductwork can help you get rid of any mould or mildew that is already growing and may even prevent this odour from occurring again in the future.

In this same way, water accumulating in the drip tray or drain pan of your air conditioner can cause mould, bacteria, and mildew growth, which can give rise to the musty smell, and it needs to be cleaned to get rid of this smell.

Cleaning frozen evaporator coils to fix a musty smelling air conditioner

When there is a blockage in the airflow of your air conditioner, this will prevent it from taking in enough warm air to cool down.

As the refrigerant continues running through the evaporator coils and there is no warm air expelled from the vents and ducts, this can cause the evaporator coils to freeze and excess moisture can accumulate in the unit’s duct or vent system.

To fix this, you can:

  • Remove and clean the air filters by running them under lukewarm water and gently scrubbing them with a soft brush or air conditioning cleaning kit, as this will remove any blockages to airflow
  • Then, you also need to let the evaporator coils thaw
  • After the ice has melted, you can clean these coils with a specialised coil cleaner to remove any mould or mildew that may have grown

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It is important to note here that leaking refrigerant may also be what is causing your evaporator coils to freeze. In this case, your coils will continue to freeze and cause the musty odour in your space if you do not get a professional to repair the leak.

Cleaning your ducts and vents to fix a musty smelling air conditioner

The best way to get mould, mildew, and bacteria out of your AC’s air vents or ducts to fix the musty smell is to hire a professional cleaner, but you can also attempt to do this yourself by:

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Cleaning your drip tray or drain pan to fix a musty smelling air conditioner

If mould continuously builds up in the drain lines and drip pan of your air conditioner, it can form into a jelly-like substance that can clog up the entire system.

To prevent mould from growing in the future and to eliminate the musty smell, you need to place drip pan or drain pan tablets in the pan if there is any still-standing water being accumulated in the drain pan of your air conditioner.

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