If you live in a state like Florida with hot and humid weather year-round, think twice about turning off your AC system when you go on vacation. If you live in a state that has below 60-degree winters, you need to turn your AC off to prevent frozen parts. Otherwise, keeping your AC unit off for extended periods is one of several reasons mold develops.
Mold in your air conditioner is dangerous to inhale and is unsightly when it has enough time to develop into visible patches. And if you’re planning on selling your home anytime soon, mold anywhere in your house can cause you to fail a home inspection.
Most of the time, a visible layer of mold signals an overdue problem.
It’s a frustrating fungus, but you can eliminate and prevent mold from creeping into your air conditioner with the proper steps and care. That goes for central AC units and smaller air conditioners like window, portable, and wall-mounted units.
So, what causes mold get to in your AC system?
What Causes Mold in the Air Conditioner?
Mold grows from microscopic spores that are all around us—indoors and out. Just as a seed develops into a plant after exposure to water and sunlight, a spore develops into mold with moisture, a dark environment, and access to organic material.
At the normal level of concentration, spores are generally harmless. However, when spores grow into mold, that mold releases more spores into the air. The higher the concentration of spores in the air, the worse it is for your and your family’s health.
We’ll talk about the adverse health effects of mold in your AC unit in a little bit.
How Common is Mold in the Air Conditioner?
According to the Centers for Disease Control and Prevention, mold is very common in homes. Because mold grows where it has access to lots of moisture and organic material, an AC unit is a prime habitat.
Organic material includes particles of wood, dust, skin, carpet, fabric, upholstery, paper, clothing, and more. The inside of your AC unit may be made of metal and styrofoam to prevent mold, but it will grow if moisture and dust collect inside.
Some parts of your air conditioner are prone to water buildup. You or a professional should check the following parts for excessive moisture at least once a year:
- Evaporator coils
- Drip pans
- Drain lines
- Air filters
- Blowers
The Dangers of Moldy AC Units
If the mold in your air conditioner builds up in filters that you don’t change or clean, your utility bills will increase as your unit works harder to cool your home, regardless of your AC’s efficiency rating. But don’t mistake mold on your AC filter as an isolated problem.
Air conditioner mold is especially dangerous because it can blow spores throughout the house. Then, the spores can settle in other moisture-prone areas like bathrooms and kitchens.
In severe cases, the mold can grow all along furniture and walls—a “wallpaper” you and your spouse can certainly agree on removing. Your health is at risk when spores are too heavily present in your home.
But what kind of mold is growing in your air conditioner?
What Types of Mold Grow in the AC?
Mold growth is fuzzy and most commonly black in appearance, but it can also be green, brown, white, pink, orange, or yellow.
Aspergillus, cladosporium, penicillium, and stachybotrys chartarum (aka black mold) are some of the most common mold types you can find in your air conditioner.
You also might have heard of or used the term “mildew” before, a generic term that people use interchangeably with mold. According to the Environmental Protection Agency, mildew usually refers to mold with a “flat growth habit.”
There are thousands of types of mold, but you should consider any mold inside your air conditioner a health risk.
Health Risks of Mold in an Air Conditioner
All of the types of mold we discussed above can adversely affect anyone’s health, especially people with compromised immune systems and mold allergies.
Spores in the air can cause:
- Sore throats
- Headaches
- Congestion
- Itchy eyes
- Various respiratory symptoms
If you have a mold allergy or asthma, you may even experience:
- Heightened reactions
- Shortness of breath
- Fever
Black Mold in the Air Conditioner
Black mold in your AC unit is particularly dangerous because it releases microscopic mycotoxins that are poisonous to humans. If you’re unaware of black mold in your AC, it could be blowing these mycotoxins all over your house.
Symptoms of black mold include:
- Chronic fatigue
- Chronic headaches
- Chronic coughing
- Chronic sneezing
- Irritated eyes, sinuses, and skin
Severe or prolonged exposure to black mold can cause:
- Nausea
- Vomiting
- Bleeding in the nose and lungs
Sometimes, mycotoxins can even lead to long-term neurological disorders.
Many species of mold release mycotoxins and are known as black mold. It’s best to address mold in air conditioners and anywhere else as soon as you become aware of it to avoid health complications.
Signs of a Moldy Air Conditioner
Now that you know what causes mold in your air conditioner and why it’s an unwelcome guest in your home, let’s talk about the signs of mold.
You might expect air conditioning mold to always present as the typical dark fuzz, but mold can be sneaky. It usually spreads inside your air conditioner before revealing itself.
You might have a mold problem in your AC unit if any of the following are true:
- You notice a musty odor when you turn on your AC
- You haven’t used your AC in several months
- Filters have gray or white powdery stains
- Energy bills are higher than normal
- Airflow is weak from return vents
- Your AC runs longer than usual
- Condensation builds on the outside of your AC
- Ductwork is misshapen or discolored
- Allergy symptoms, like itchy eyes and stuffy nose, appear while the AC runs
If you experience any of these, it’s best to safely and immediately have a professional inspect your air conditioner.
What To Do About Air Conditioning Mold
Should You Throw Away a Moldy Air Conditioner?
If you see mold on the grate of your smaller air conditioner, it’s time to replace it. Once the mold reaches a stage of visible growth, expect the mold to grow back even after cleaning.
Visible mold growth on one-third or more of the internal surface area of your smaller air conditioner calls for a replacement unit. If mold covers less than one-third of the surface area and you have the time, you can try cleaning it yourself.
If you have an HVAC system, your best bet is to hire a professional mold remediation service. Unless you’re an experienced mold technician, you won’t be able to safely reach all areas of the ductwork or inner workings of the unit itself.
How to Clean Mold From an Air Conditioner
The most significant benefit of cleaning your own smaller AC unit is that you will save the cost of hiring a professional to inspect your unit, which we outline in the next section.
But cleaning the mold out of your smaller AC unit is difficult, and you should be aware that the mold may resurface.
Here’s what you need to confront the mold in a smaller air conditioner:
- Goggles
- Face mask, like an N95 or surgical mask
- Rubber gloves
- Screwdriver
- Outdoor space to clean
- Water
- Bucket
- Bleach
- Sponge or rag
- Detergent
- Vacuum cleaner
Steps for cleaning your air conditioner of mold:
- Protect yourself from extended exposure to mold by wearing rubber gloves, goggles, and a face mask.
- Unplug your AC unit and take it outdoors to your designated cleaning area, such as the driveway.
- Depending on your air conditioner, you may have to use a screwdriver to open the unit and remove its filter.
- If the filter is disposable, put it in a plastic bag to throw away and skip to Step 8. If it is not, follow the next steps to clean it.
- Prepare a bucket with a mixture of one part bleach to 10 parts water.
- Clear any visible mold debris from the filter and submerge it into the mixture for at least 10 minutes.
- Rinse the filter with water and allow it to air dry.
- Clear the dust and debris inside the AC unit using a vacuum cleaner. Remember that dust is food for mold.
- Rinse the bucket and make a new mixture of one part bleach and 10 parts water plus a tablespoon of detergent for added infiltration.
- Using a sponge or rag, thoroughly clean the unit, avoiding electrical parts.
- Rinse the unit with water, avoiding electrical parts, and allow it to air dry.
- Return the filter, reassemble any parts you unscrewed, and plug the unit back in.
Does vinegar kill mold in the air conditioner?
Vinegar can kill mold because of its acidity, but its power is limited and you should not use it if the mold has infected the inside of your unit. Mix a cup of white vinegar with a gallon of water, and spray the solution on moldy surfaces.
Will Lysol kill mold in the air conditioner?
Lysol kills mold because it contains hydrogen peroxide. Once mold reaches your air conditioner, however, it’s best to call a professional instead of trying to spray Lysol.
Call a Professional Service
Despite the cost, we recommend hiring a professional mold remediation service to clean mold from a central AC unit. The infestation may be too intricate or severe to safely manage yourself.
A pro can identify additional signs of mold that you might miss and handle the mold without damaging crucial components. They may include preventive measures to save you the hassle of mold in the future, like pinpointing clogged drains and areas of excess moisture.
Overall, a professional mold remediation service pays off because it provides a safe and permanent solution.
Cost of AC Mold Removal
Mold removal is expensive, especially if the mold in your air conditioner develops for too long. For central AC units, the best solution is hiring a professional mold removal service.
Hiring a professional to remove mold from your air ducts costs anywhere from $1,000 to $2,000. Depending on the severity of the mold, hiring a professional to clean your entire central AC unit costs between $2,000 to $8,000.
With smaller air conditioners, it’s best to replace the unit. The cost to hire a professional to inspect these units will most likely be higher than just buying a new one.
Replacing a window AC unit costs between $150 and $600. Portable AC units cost between $250 and $500. Wall-mounted AC units cost between $400 and $1,000.
How to Prevent Mold in the Air Conditioner
You can take several actions to prevent mold from ever developing in your air conditioner. Remember that the goal is to deprive spores of access to moisture and organic matter. That means keeping your air conditioner dry and dustless as much as possible.
Tips to Prevent Moisture Buildup in Your AC
- Avoid using water for any HVAC system cleaning.
- Ensure your HVAC system has a drainage system.
- Empty drip pans and rinse with bleach regularly.
- Keep your AC grates and return air vents unblocked and clean throughout the house.
- Regularly check for leaks and have any you find repaired.
- Use a dehumidifier if your home is humid.
- Invest in an AC with humidity control.
- Seal and insulate ductwork to minimize condensation in your HVAC system.
- Ensure window AC units fit tightly in the window to prevent rain and humidity from entering the unit.
- Keep window units tilted back to drain condensation.
Tips to Prevent Dust Buildup in Your AC
- Keep the area around your AC clean.
- Clean grates and reusable filters once a month.
- Replace air filters regularly according to the manufacturer’s instructions.
- Buy an air filter with a higher MERV (minimum efficiency reporting value) rating.
Other Tips to Prevent Mold in Your AC
- Have a professional inspect your AC yearly.
- Run the AC while on vacation to keep spores from settling. Turn up the temperature about ten degrees so that the AC turns on intermittently while you’re away.
- Install a UV light air purifier that kills airborne spores in your HVAC system.
Break the Mold
The air you and your family breathe at home is precious. Serious health and financial consequences come with ignoring a moldy AC unit, but you can take steps right now to protect your home.
Now that you know all about mold, it’s time to show it who’s boss—whether that’s with some elbow grease or a professional service.
Above all, we recommend prevention to ensure the fungus never gets a peek inside your lovely home.