Mold on AC Vents? Here’s How To Clean, Kill & Get Rid Of It

Mold is a type of fungus that can form anywhere, including our homes. It causes health complications when we get exposed to it. As an HVAC professional, people often ask me how to remove mold from AC units safely.

Molds in the AC vents can quickly spread spores in the air to fill up the house, making everyone sick. Today, I’ll tell you how to clean mold from air conditioner vents without damaging the AC unit.

Mold in AC Vents

What Causes Mold In Your Air Conditioning Vents?

As long as there’s moisture and the temperature is warm, molds will form in the air conditioning vents.

Here are the common causes of mold on AC vents.

Climate, Moisture & Humidity

The main ingredient for mold formation is water vapor. And, in a humid climate, there’s usually moisture in the air, which gets trapped in walls. The condensation process then happens, causing mold to grow on the air conditioning vents.

Poor Ventilation

Imagine air trapped in a house where there’s poor ventilation. The moisture trapped in the walls will soon become stale since it can’t escape, and in no time, there will be a musty odor.

The stale moisture then forms mold around the AC vent in the bathroom and other damp places.

Oversized AC Unit

If there’s one thing we encourage as HVAC professionals, every homeowner should install a suitable AC unit for their space. There’s always the correct size for every room.

Installing an oversized AC unit in a small space encourages mold formation. Such AC will provide quick cooling but will turn off before removing the excess moisture from the house. This moisture will then cause mold in the air conditioning vents.

AC Is Being Run Too Cold

Low temperatures can also cause mold formation in the air conditioning vents. When this too cold air mixes with the room’s warmer moisture, condensation happens.

This moisture build-up, in return, causes mold to grow in the AC vents.

Signs of Mold In & Around Your AC Venting

There are various signs of mold in and around the AC venting, including odor, visible mold, mildew, and allergy reactions.

Musty Odors

Mold smell coming from AC vents is usually the first sign one experiences. The trapped moisture becomes stale in a poorly ventilated home, and soon there will be a persistent foul odor, especially if the AC is running.

Usually, the musty smell becomes quite strong near the AC unit. If the mold stays there for long, the whole house will soon be in havoc. I recommend you call for professional help the first day you smell this musty odor to prevent mold from spreading further.

Visible Mold & Mildew

Sometimes, mold and mildew in vents and around the air ducts become so big that one can easily spot them. This formation happens after the AC condenser coils extract moisture from the warm air, settling in and around the AC vents.

By this time, the mold infestation becomes so severe that one must quickly look for ways to remove it.

Allergy-like Symptoms

Here is another obvious sign of mold growing in and around the AC vents. The biggest side effect of being exposed to mold is feeling sickly. Whoever breathes in tiny mold spores will most likely suffer from allergy-like symptoms.

Homeowners might experience headaches, nasal congestion, nausea, itchy eyes, irritated throat, and skin rashes.

With such illnesses, I highly recommend stopping using the AC unit until the mold is cleaned out. Prolonged exposure to mold spores can make the situation even worse.

Signs of Mold in Vents

How To Kill Mold In Your AC Vents

We understand now how great of a threat mold is to our health. So, I’ll discuss how to clean air conditioner vents to help remove molds.

Here are five easy ways of how to kill mold in AC vents.

Use Laundry Detergent

Using laundry detergent is ideal for DIY enthusiasts who want to kill mold in their AC vents.

Before starting this process, one must wear gloves and a mask to avoid direct exposure to this deadly fungus. Also, remember to turn off the AC unit. Follow this step-by-step guide for excellent results.

  1. Using a screwdriver, remove the AC vent grill and put it in a basin full of water mixed with a few drops of laundry detergent.
  2. Ensure it’s soaked for about 15 minutes before rinsing.
  3. While still soaking, take this opportunity to get rid of dust and other debris using a HEPA vacuum. Later, wipe the inner parts with soapy water, spray using a disinfectant and leave them to dry out completely.
  4. Now take the vent grill out and rinse it thoroughly. This part must also dry completely before screwing it back to the system.
  5. After reattaching the vent grill, get rid of everything used in this process as a safety precaution.

Use Dawn Dish Soap

Dawn Dish Soap is heavy-duty, making it perfect for this task. Here’s the process of killing molds in AC vents using Dawn Dish soap.

  1. Remove the air vent grill from the system and put it in a large basin filled with warm soapy water.
  2. While this part is soaking, use a HEPA vacuum to clean the inner air vents. Afterward, take a scrubbing brush to remove any stubborn debris from the air vents and leave it to dry out completely.
  3. Attach the vent grill back to the unit.

Use Detergent & Baking Soda

Detergent and baking soda is a more powerful version of killing mold than using laundry detergent. Below are the steps you should follow.

  1. In a basin, add one tablespoon of either laundry or dish detergent, one cup of water, and a half tablespoon of baking soda.
  2. Unscrew the AC vents and put in this solution. Note: the vents need to submerge in this solution fully. If they don’t, increase the ingredients in the same ratios I specified above.
  3. Let it soak for 15minutes. Meanwhile, use a HEPA vacuum to clean the inner parts.
  4. Once vacuumed, use a long mop to wash the interiors using the same solution.
  5. The next step is to apply a scouring brush on all the parts to remove any remaining debris and leave them to dry before reattaching the air vents.

Use Bleach

Bleach is perfect for a non-porous surface. Remember to always use the manufacturer’s instructions when handling bleach. Before anything, ensure the AC is off.

  1. Combine bleach and water as indicated on the bleach package
  2. Divide this solution into two parts
  3. Vacuum the non-porous surface using the HEPA vacuum
  4. Dip a rag in water-bleach solution, then use it to wipe and clean the outer air vents
  5. Remove the air vents, dip in your cleaning solution and leave to soak for up to 15minutes
  6. Use the second part of the solution to clean the inner vents and leave to dry
  7. After 15minutes of soaking, remove the vent grill from the cleaning solution. Then, using a scrubbing brush, wash and scrub off any left debris.
  8. Rinse and leave to dry completely before putting it back in the system.

Mold Killer Products

There are a lot of mold killer products that one can use to kill mold from the air vents. Before buying, ensure it’s EPA approved. For safety purposes, wear a mask and a pair of gloves.

Then, use the same process used in all the other three, but this time, use a mold killer product instead of the above cleaning solutions. Discard everything used in this process after reattaching the vent grill.

Use the above cleaning processes when asked how to clean an air conditioner return vent.

Is Black Mold In Your AC Vents Dangerous?

The most straightforward answer to this question is yes, this type of mold is quite dangerous. The moisture inside the AC vents is responsible for this type of mold growth.

Black mold on AC vents comes with a lot of health complications, making it hazardous. It’s mostly linked to respiratory-related complications.

Breathing in spores from black mold can make one experience the following health issues.

  • Irritated Eyes, Nose or throat
  • Fatigue
  • Diarrhea
  • Frequent headaches
  • Rashes
  • Chronic coughs
  • Lack of concentration
  • Breathlessness
  • Nausea
  • Vomiting
Types of Molds

How To Prevent Mold Growth In Your AC Vents

The above processes can help kill mold on AC vents, but there’s no guarantee the molds won’t grow again. A better alternative is to take preventive measures to stop mold infestation.

Here are excellent tips on how to prevent mold on AC vents.

  • Apply an EPA registered mold growth inhibitor on the air vents after cleaning.
  • Replace the air filters regularly.
  • Clean the drip pans frequently to discourage mold growth.
  • The moist areas surely need a reliable dehumidifier.

I’d also advise hiring a qualified technician for regular ventilation inspections. This professional must do everything possible to prevent mold growth on the air vents and any other part of your home.

People Also Ask (FAQ)

Is mold in AC vents common?

Mold in AC vents is very common in warm and humid environments. This is because, along with poor ventilation, the moisture gets trapped in the walls. Afterward, the condensation process happens, causing mold to grow in AC vents.

Will Lysol kill mold?

Lyson is a product used to make mold and mildew remover sprays. So, yes, it can kill mold. However, many people have complained about mold growing back after using it.

Does vinegar kill mold in air conditioners?

Yes, it kills. Put water and one cup of vinegar in a spray bottle, then shake well until fully mixed. Spray the solution in your air conditioner to get rid of mold growing there.

Does air duct cleaning get rid of mold?

Yes, air duct cleaning is an effective way of removing mold.

How do you clean mold from window air conditioner vents?

Start by turning the window AC unit off, then removing the body grille. Afterward, remove and wash the filter. Proceed and vacuum the AC’s interior to get rid of dirt. Use a brush and cleaning solution to scrub the areas affected by mold. Wait for 15 minutes, then rinse the AC vent.


Breathing in mold spores is very dangerous for our health. It worsens when mold grows on the AC vents since the spores can spread to fill up the entire house. Thankfully, after reading this article, homeowners can now get rid of mold growing in the AC vents and live a healthy life.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.