Air conditioner problems can be determined by sounds and smells. A smelly air conditioner may indicate mold, mildew, refrigerant leaks, and even overheating with the smell of burning plastic. If an air conditioner smells like urine, the odor is also an indicator of an ongoing problem within the air conditioner.

Burning smell coming from your unit immediately tells you something is overheating and burning in your AC unit. However, you may be pleased to know that urine smells don't automatically mean there's urine in your air conditioner! Most likely, the cause of the pee smell comes from bacteria, mold, or mildew that emits the odor:

Air Conditioner Smells Bad: 3 Causes of Urine Smell in AC System

Cause #1 Ammonia-emitting Bacteria

A study done by Dr Lai Ka-man and his team in Hong Kong Baptist University found seven varieties of bacteria feast on dead skin cells, dust, and organic debris in air conditioner filters emit ammonia, causing air conditioner smells like urine and sweat.

The staphylococcus haemolyticus, which is abundant on the surface of the skin and in animal fur, contributes to air conditioner smells, and was found in a notable number of samples from their study. The bacteria is not directly harmful to healthy individuals, but a large concentration of bacteria may cause skin and respiratory infections, and compromise those with low immunity.

Because the bacteria feed off skin cells and other organic particles, they can be found in the air filter and filthy evaporator coil.

Cause #2 Mycotoxins from Mold

If your central air conditioner smells like urine, there is a high chance you have mold in your air vents or air filter. Mold in your vents reduce the indoor air quality, and can cause allergies, nasal congestion, asthma attacks, and other mold exposure symptoms.

Mold creates mycotoxins, which emit that musty odor that we attribute to mold. However, different species of fungi can cause different smells. The same study done by the Department of Biology, Hong Kong Baptist University identified four species of fungus that grows in air cooling systems that emit urine-like smells.

Expelling mold from your air conditioning system relies on finding the source of the mold. Our HVAC technicians will be able to check your cooling system for the source, and eradicate the mold colony from your home. However, you will need to have your air conditioning system checked every 3-4 months to make sure the mold growth does not return.

Cause #3 Household Pests

Perhaps among the more unsavory reasons, household pests may be contributing to the urine smell coming from your air conditioner as they turn your AC unit into a litter box. Rodents and other vermin may relieve themselves on your home or car air conditioner to mark their territory, causing the urine smell in your vents.

Decomposing carcasses of rodents and birds may also give off a urine-like or rotten eggs smell from ammonia and sulfur that the decaying organic matter emits. If an animal has crawled into your vents, it could have expired in your home air conditioner, causing that pee smell to come from your air conditioning unit.

Use natural deterrents to ward off pests from entering your vents, and install thick screens to prevent rodents from getting into your home through small openings in your windows, doors, and other entryways.

How to Remove the Urine Smell from Your AC Unit

Clean the Air Filter

Cleaning your air filter will get rid of the food source for bacteria and fungi, which may be causing the home and car air conditioner smells. Take the filter out of your air conditioner, and run it under the tap. Use a brush to remove the dust and debris, and apply an antibacterial soap to kill any remaining microbes. Let the filter dry before placing it back into your unit.

Cleaning the filter also removes the musty air conditioner mildew smell, as well as allergens in the air. If your air conditioner smells like urine even after cleaning the filter, have a professional air cooling company inspect and deep clean your air conditioner to remove the odor for good.

Regular Cleaning and Maintenance

Regular air conditioner cleaning and maintenance is done by our experienced and knowledgeable HVAC technicians. Professional cleaning services will get rid of air conditioner smells like rotten eggs, dirty socks, and urine smells. Regular cleaning every 4-6 months will help keep your air conditioner pristine.

Maintenance will make sure your air conditioners stay in tip top shape! Get rid of the dirty sock syndrome, leaking air conditioners, and faulty AC parts before they become problems. An air conditioner tune up will lengthen the lifespan of your air conditioner, so it is best to look into maintenance schedules once every 6 months.

Keeping Your Air Conditioner Odor-free

The best way to keep your air conditioner clean and odor-free is to have professional maintenance services check your unit. Our technicians at Luce Aircon will be able to determine why your air conditioner smells bad, and fix the problem for you before it becomes a health hazard. Trust in us to get your air conditioner to its optimal condition!

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Check out our article on why ac smells like feet!