How common is mold in air conditioners?

Author: Ernest Collins IV  |  Last update: Thursday, August 28, 2025

Mold in air conditioners is a common problem since they have warm, moist areas that don't get much light. Unfortunately, your air conditioner can become a prime target for mold growth if it is not properly maintained.

Is it normal to have mold in an AC unit?

But mould can easily build up in your air conditioner when it's left untouched for long periods of time. If you want to save some power, you can turn up the target temperature so that your air conditioner isn't running for long periods of time.

What are signs of mold sickness?

Although symptoms can vary, the most common symptoms seen in people exposed to mold indoors include:
  • Nasal and sinus congestion.
  • Eye irritation, such as itchy, red, watery eyes.
  • Wheezing and difficulty breathing.
  • Cough.
  • Throat irritation.
  • Skin irritation, such as a rash.
  • Headache.

What temperature should the AC be to prevent mold?

The optimal temperature to discourage mold growth is around 77-78 degrees Fahrenheit. At this temperature, your AC will effectively remove moisture from the air, which is a key factor in mold prevention.

How long does it take for mold to grow in AC?

Mold can grow extremely quickly once you start to have moisture building up in the air ducts of your HVAC system. Within just 48 hours of that moisture being present, mold can begin to form and once it does, when the air passes through, so will the bacteria and such from the mold throughout the rest of the home.

MOLD in HVAC System or Ductwork!

What kills mold in AC?

Best way to clean mold growth in the AC units

Steam cleaning kills up to 99.9% of germs and will leave your central air conditioning system not only clean, but sanitized as well, getting rid of all the mold spores and musty odors.

What temperature should I keep my house to prevent mold?

Keeping the air conditioner set at 78 degrees or lower prevents mold buildup in the summer. Even when leaving for a few days or vacation, don't set it above 80. A higher setting won't provide enough dehumidification from the cooling process to prevent spores from growing.

How do I test my AC for mold?

Take a look inside the air conditioner unit's ductwork and coils. Shine a flashlight inside to check for any visible signs of mold growth. If you spot mold, it's essential to address the issue promptly.

Do fans help prevent mold?

Ventilation fans are the best way to prevent mold build up inside a home. Think about it: what happens when a home has a flood? Typically, a water damage expert will be called in and the first thing they do is bring in ventilation fans to dry out the moisture and wetness inside the home.

What temperature kills all mold?

Most yeasts and molds are heat-sensitive and destroyed by heat treatments at temperatures of 140-160°F (60-71°C). Some molds make heat-resistant spores, however, and can survive heat treatments in pickled vegetable products. These molds, however, require oxygen to grow.

How common is mold in homes?

In a 2022 report, the National Institute for Occupational Safety and Health Centers for Disease Control and Prevention estimated that around 47% of all homes in the United States have some mold or dampness, based on several published studies.

What does black mold smell like?

Black mold has a distinct smell. It's often described as musty and earthy and may even smell like rotting vegetables, plants, or paper. Some think it smells like cedar.

How much does it cost to remove mold from HVAC system?

The cost to remove mold from an HVAC system is $2,000 to $10,000, depending on the system type and whether the mold has spread into the ductwork.

Do AC filters help with mold?

Your HVAC air filters can trap mold spores and keep them from being blown into the air as it circulates throughout your home. You should change your filters every 30-90 days, depending on the filter type and quality.

How to clean inside an air conditioner?

Turn off the power to your air conditioner. Locate the evaporator coils, which are typically found inside the indoor unit or air handler. Carefully remove the access panel or cover to expose the coils. Use a vacuum cleaner with a soft brush attachment to remove dust and debris from the coils gently.

How to keep AC from molding?

Preventative Measures
  1. Regular Cleaning: It's important to clean the filter and interior surfaces of your air conditioner regularly. ...
  2. Inspect and Clean Internally: Beyond the filter, ensure the coils and water pan inside the unit are also cleaned to prevent dirt build-up that can hold moisture and foster mold growth.

How do I keep my room mold free?

Reduce condensation and black mould growth
  1. Produce less moisture. There are lots of things you can do to reduce the amount of moisture in your home. ...
  2. Remove excess moisture. ...
  3. Ventilate. ...
  4. Keep your home a little warmer. ...
  5. Insulate your home. ...
  6. Remove black mould.

Does leaving an AC fan on increase humidity?

Leaving your AC fan set to ON allows the moisture in your home to accumulate and reach mold-growing levels of humidity. To ensure that you and your family stay cool and healthy this summer, keep your AC thermostat fan setting to AUTO.

Is mold in AC common?

Mold in air conditioners is a common problem since they have warm, moist areas that don't get much light.

Does home insurance cover mold?

Homeowners insurance doesn't usually cover mold damage or removal unless it's the result of a covered peril. If the mold in your residence was caused by something sudden or accidental, such as a bursting pipe or some other covered incident on your policy, you may be protected.

Should mold be professionally removed?

You can save a little money with DIY mold cleaning, but there's no guarantee that you can stay safe or get rid of the mold for good. In cases with larger areas of mold growth, professional mold removal is the best option.

What does mold hate?

Mold hates light. Other than moisture there's nothing mold loves more than dark places. An easy prevention against mold growth is opening your blinds and shades. If it's warm enough out, open the windows.

Should I keep my thermostat on auto or fan?

"ON" keeps the fan running continuously, which can help with air circulation and filtration but may consume more energy. Choose "AUTO" for energy savings and "ON" if you want constant air circulation or improved air filtration.

Does turning AC off cause mold?

How does keeping my AC running prevent mold and pests? Air conditioners help reduce indoor humidity levels, which can create ideal conditions for mold growth and pest infestations. Running your AC at a slightly higher temperature while you're away can maintain lower humidity and prevent these issues.

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