How to remove mold in air conditioners

Black mold in air conditioner

Air conditioners provide much needed relief from summer heat and more importantly, helps create unfavorable conditions for mold growth within your home. However, the inside of your unit can be a mold breeding ground. If this is the case, spores blow out and spread throughout your home whenever your run it which causes allergy symptoms in family members and pets. We will reveal some black mold in the air conditioner tell tale signs, how to remove it and what you can do to prevent it.

Topics covered
  • Signs of mold in air conditioners
  • What causes mold in air conditioners?
  • Removal methods
  • Prevention methods

What are the signs of mold in air conditioners?

It’s highly unlikely that you will notice black mold in your air conditioner until the infestation has reached a certain level. Common signs to look out for include a musty earth-like odor and flaring up of allergies whenever it’s in use. Also, it’s important not to run the system if you are fairly confident that the ac unit is the source of the problem.

What causes mold to form in air conditioners?

Mold in air conditioning units is mostly the result of not cleaning the system or having regular maintenance done on it. Over time, your ac unit will attract and collect sufficient amounts of dust and dirt from both outside and from within your home which mold can feed on.

Therefore, cleaning the ac and having yearly maintenance done on it pays off in the long run because as we all know, mold deteriorates and destroys the surfaces it grows on. And if it finds its way onto important components and places within the system such as styrofoam and coils then the system won’t function 100% effectively and eventually cease to work – all the while making the house occupants sick.

Another cause is leaks within the system itself. This is usually the result of an incorrectly installed system or due to lack of maintenance. The water which accumulates attracts more dust than usual and both the water and dust fuels mold growth within the air conditioner.

How to clean mold from the air conditioner

Removing mold in the home is in most cases an easy and straightforward process but when it comes to air conditioners the task can become extremely tricky because of the many hard to reach places. In most cases it would be best to call in an expert to do maintenance and cleaning on your entire system because if mold is present on the styrofoam and coils then it would likely need to be replaced. Also, cleaning out the duct and other hard to reach places is no easy task. In other words, a professional will be able to service and clean out your entire system – thereby ensuring that all traces of mold in the air conditioner unit as well as its allergy causing spores have been removed.

If you still want to do it out yourself then we will show you how to clean the easy to reach places.

Safety measures:

  • Respirator: Spores will more than likely be released during the cleaning process and although potentially harmless, could trigger allergic reactions in susceptible people. Therefore, wearing a N-95 respiratory mask is recommended.
  • Gloves: Protect your hands with a pair of ordinary household rubber gloves because bleach will be used as the main cleaning solution.
  • Safety glasses: The last thing you want is to get bleach into your eyes. Protect yourself with a good pair of wrap around safety glasses.
  • Windows: Spores and bleach fumes can be harsh when working in a small confined space. Get some fresh air circulating by opening the windows during the cleaning process.
  • Clothes: Wear old clothes you can wash once you are done cleaning because spores stick to clothing and bleach can stain.

Cleaning solution: Mix some luke-warm water with normal dish washing liquid. This will be used for most of the washing and wiping down. We will also be using bleach because it’s an excellent disinfectant and does a great job at killing spores. The bleach will also be directly applied to any visible mold growth on the ac unit.

To prepare your bleach solution simply mix it with water to a ratio of 1:10. You can use this solution in a container and apply it with a sponge or cloth or add it to an easy to use spray bottle.

Step 1: Turn off the power to the ac unit. This is important because you could come into contact with electrical components.

Step 2: Clip off the face / front panel of the ac unit and clean it on both sides with warm soapy water and a cloth. If mold is present on the backside of the panel then spray some bleach directly onto it and scrub with a brush until it comes off.

Step 3: Remove the ac filter and thoroughly HEPA vacuum it to suck up all the dust and spores it collected. Afterwards, let it soak in some warm soapy water for an hour.

Step 4: Insert the hepa vacuum as far as it will go into the ac unit to vacuum up as much dust, dirt and spores as possible.

Step 5: Wash wherever you can reach with warm soapy water and wipe it down with your bleach solution afterwards.

Step 6: Wait a few hours for everything to dry before reassembling the front face of the air conditioner unit.

Step 7: Open the air intake unit located outside. It’s held in by screws so you will need a screwdriver to take it apart.

Step 8: Once open vacuum and clean everything within reach, including the fan. Wipe everything down with your bleach solution.

Step 9: Screw the cover back on and allow a few hours for everything to dry before turning the power back on and using it.

How to prevent mold in the air conditioner

Keeping mold out of your air conditioner is the best way to ensure you have clean air circulating throughout your home and there are a number of steps you can follow to do this.


HEPA filters: All air conditioner units come fitted with air filters. The problem with these filters is that they only block out the larger particles – and they are there for the sole purpose of protecting the components of the unit and not your health. Fortunately, there are HEPA filters available for these systems which will prevent microscopic mold spores from entering the air conditioner and ultimately your home.


UV filters: Most new air conditioners available for purchase today comes with a bacteria killing UV light filter already fitted. In many cases, a UV filter can be purchased separately and fitted on the current AC unit. This filter eliminates up to 99% of all viruses, bacteria and mold spores without putting any additional strain on your unit. Read more about the best mold proof UV filtered air conditioners here.


Yearly maintenance: It’s recommended to have a professional come in annually to thoroughly clean and do maintenance on your air conditioner. Air filters and drain pans need to be cleaned and replaced while air ducts should be cleaned and dried.


Control the situation within your home: About half of the mold found within your AC unit and vents came from within your home. This can easily be prevented by controlling your indoor environment. If your home is humid then it might be wise to invest in a good quality dehumidifier. This will prevent excessive moisture within your living environment which feeds mold and encourages its formation. Additionally, a HEPA filtered air purifier and regular vacuuming with a HEPA vacuum cleaner will drastically reduce the amount of spores.


Monitor the area around the air intake: Many people do not know this but you can drastically cut down the chances of spores making their way into your air conditioner by monitoring the area near and around the outside intake system. Simply make sure that there are no bird droppings, trash cans or standing water near the outside intake system.

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