Your air conditioner can sometimes "speak" through unusual smells, signaling that something isn’t right. In Singapore, where aircon units are often running around the clock, these odors can indicate issues like mold, refrigerant leaks, or overheating.
A burning smell suggests something is overheating in the system, while a smell like urine usually points to bacteria or mold buildup–and not literal urine!
Check out the ultimate causes of urine smell in the aircon system, and what you can do to remove them. Addressing these issues promptly ensures your home remains a cool and clean haven.
4 Causes of Aircon Smells Like Urine
Cause #1 Ammonia-emitting Bacteria
A study done by Dr Lai Ka-man and his team at 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 reduces 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 grow 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
In Singapore, the warm and humid climate creates the perfect environment for pests like rodents, cockroaches, and lizards to seek shelter inside homes and buildings. Unfortunately, air conditioning units and ducts can become unintended hiding spots for these pests. Rodents, in particular, may leave urine and droppings inside or around the AC system, which can lead to an ammonia-like smell.
We've encountered cases like this in some of our clients who discovered that a persistent urine-like odor from their AC was due to rodent activity in the ducts or indoor unit. Given Singapore’s dense urban landscape, pest infestations in AC systems can be more common in older buildings or units with poor maintenance.
Cause #4 Contaminated Ductwork
High humidity levels can contribute to moisture buildup inside AC ducts, leading to mold and bacterial growth. Over time, if the ductwork is not regularly cleaned, dust, pet dander, and even pest droppings can accumulate, creating an unpleasant musty, or ammonia-like odor. In some cases, older buildings or office spaces with centralized air conditioning systems might experience this issue if their ductwork has not been cleaned for years.
We've seen clients in Singapore complain about lingering odors even after cleaning their AC units, only to find out that their ductwork was the real culprit. If left unchecked, dirty ducts not only cause foul smells but can also affect indoor air quality and trigger allergies or respiratory issues.
How to Remove the Urine Smell from Your AC Unit
Clean or Replace 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.
Do keep in mind that you might need to buy a new air filter for AC once every 4 months. If you live in a busy or dusty area in Singapore, you might need to replace it more frequently.
But, if your air conditioner still 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.
Consider Using an Air Purifier
Given Singapore’s humidity and urban pollution levels, an air purifier can help reduce airborne bacteria, mold spores, and odors in your home. If your AC system has a lingering smell even after cleaning, using a HEPA air purifier or an activated carbon filter can help neutralize the odor while improving indoor air quality. This is especially beneficial for those living in high-rise apartments or office buildings where external ventilation is limited.
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.
Additionally, 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 AC maintenance services check your unit. Our technicians at Luce will be able to determine why your air conditioner smells bad and fix the problem for you before it becomes a health hazard.
Luce ensures cleaner air and peak performance with our comprehensive air conditioning servicing, trusted by homes and businesses alike across Singapore. Trust us to get your air conditioner to its optimal condition!
Check out our article on why ac smells like feet!
