Why Your Air Conditioner Smells and How to Fix It

June 20, 2023

When your air conditioner starts spewing odd or unappealing aromas, it is a good idea to take notice because it could be a sign of a big problem. Ignoring unpleasant smells coming from your air conditioner could lead to serious damage to your AC or even pose a risk to your health and safety.

Depending on the smell, the root of the problem might be bacteria or fungus in the system. Other times, it could also sign something mechanically wrong with the air conditioning system. Some smells are even indicative of a hazardous situation, like a natural gas leak.

At A&M Heating & Cooling LLC, we have a nose for these sorts of things. If you smell something weird coming from your cooling system, you can bet that our team of talented pros has smelled it, too—and fixed it! We’ve earned the reputation as the premier company for air conditioning repair in Tucson.

What does a specific odor coming from your cooling system mean? Here are several frequent air conditioner smells and what they may mean:

My Air Conditioner Smells Like Feet

If your air conditioner smells like feet, it can be caused by a buildup of bacteria or fungus in the system. When moisture builds inside the unit, it can create an environment that is conducive to the growth of bacteria and fungus. This can produce a bad odor that is often described as smelling like feet.

Another likely explanation for the smell could be a dirty air filter. When your HVAC system's air filter becomes filled with dirt, dust and other particles, it can cause low air quality and a musty smell that resembles feet.

To solve this unpleasant situation, it's important to have an experienced specialist inspect and clean your air conditioning system, including the evaporator coil, drain pan and condensate drain line. It's also important to exchange the air filter regularly to ensure good air quality and prevent the development of bacteria and fungus.

My Air Conditioner Smells Like Rotten Eggs

If your air conditioning unit smells like rotten eggs, it might be because of a natural gas leak in the unit or in the surrounding area. Natural gas has a unique odor, often described as smelling like rotten eggs or sulfur, that is added to it to make it easily detectable.

A natural gas leak is extremely dangerous and requires immediate attention. If you suspect a gas leak, turn off your air conditioning system, immediately open windows and doors to ventilate the area, make everyone leave the building and call your gas company or emergency services right away.

My Air Conditioner Smells Like Mildew

If your air conditioner is giving off an odor like mildew, it could be due to a collection of moisture inside the unit. When moisture accumulates inside an air conditioner, it can promote the growth of mold and mildew. This can cause a musty odor that bears a resemblance to mildew.

Another possible explanation for the smell may be a clogged air filter. If the air filter becomes clogged, it can result in poor air quality and a musty smell that resembles mildew.

Routine air conditioning maintenance from A&M Heating & Cooling LLC can help prevent both of these situations, because a good cleaning, inspection and filter change is a great way to keep your system operating at its best!

My Air Conditioner Smells Like Urine

One of the most undesirable things is when the air coming out of your HVAC system smells like urine.

If your air conditioner stinks like urine, it could be traced back to a number of things. One likely cause is a collection of bacteria or mold in the your HVAC. This can happen if moisture accumulates in the system and creates a moist environment that can promote bacterial growth. The bacteria can create a foul odor that it similar to urine.

Another possible cause of the stink could be a clogged drain line. The condensation that forms inside the air conditioning unit needs to drain away correctly, but if the drain line becomes choked with debris, it can cause water to back up and build up inside the unit. This can produce a musty smell that resembles urine.

My Air Conditioner Smells Like Burning Plastic

If your AC smells like burning plastic, this could indicate an electrical concern with the unit. After some time, the electrical components in the air conditioning system can wear out or break, which can create a burning smell that resembles plastic.

Another possible root cause of the smell could be a foreign object that somehow got in the unit. If something foreign gets trapped in the air conditioning system, it can get hot and result in a smell like burning plastic.

If you notice something that smells like burning plastic coming from your air conditioner, it’s essential to contact a professional right away.

My Air Conditioner Smells Like Gas

If your air conditioner smells like gas, it could be due to a natural gas leak in the unit or in the surrounding area. Natural gas has a distinctive smell, often described as smelling like rotten eggs or sulfur. That’s because this scent is put into natural gas to make sure that it is easily detectable.

As mentioned earlier, a natural gas leak can be VERY harmful and requires immediate attention. If you suspect a gas leak, turn off your air conditioning system, open windows and doors to air out the home, evacuate the building and contact your gas company or emergency services right away.

Why My Air Conditioner Smells Like Fish

Should your AC smell like fish, you may have a situation where there's a build-up of bacteria or mold in the unit. Moisture causes an environment that promotes the growth of bacteria and mold. This can cause a strong odor that can be described as smelling like fish or, as mentioned earlier, it also can cause a smell like dirty feet.

Another possible cause of the smell could be a dead animal or other biological material caught inside the air conditioning system. This often is possible if an animal such as a mouse or bird is trapped inside the unit and dies.

To fix the issue, it's worthwhile to have a professional examine and clean your air conditioning system. They should be able to find the source of the smell and take the correct steps to remove any contaminants and stop the problem from recurring.

Why My Air Conditioner Smells Like Vinegar

There could be numerous reasons a home's air conditioner smells like vinegar. One possible cause is a dirty air filter. Another possible cause of the smell might be a refrigerant leak. When the refrigerant leaks, it can make a chemical odor that is similar to vinegar.

To fix the issue, it's essential to have a skilled mechanic inspect and clean your air conditioning. If the odor continues after the cleaning and replacing of the air filter, it's best to reach back out to a professional to diagnose and repair any persistant issues with your air conditioning. Or, they can tell you if your air conditioning ought to be replaced.

If you are looking to upgrade, A&M Heating & Cooling LLC can help select the correct unit to fit your home’s needs. We provide dependable, skilled air conditioner installation in Tucson.

My Air Conditioner Smells Like Chemicals

If the smell of chemicals is coming from your air conditioning equipment, it could be due to a refrigerant leak. When the refrigerant leaks, it can create a chemical scent that people sometimes describe as smelling like chemicals or paint thinner, vinegar or acetone.

An additional possible source of the smell could be a problem with the electrical wiring or elements inside the air conditioning system. This can cause a burning smell that is like chemicals or burning plastic.

If you believe there is a refrigerant leak or an electrical issue, it's important to turn off your air conditioning system immediately and contact a professional to inspect and repair the unit. Refrigerant leaks can be dangerous and may require immediate attention to protect against injury or damage to your home.

Strange Smell Coming from Your AC? Call the Pros at A&M Heating & Cooling LLC

If your air conditioner stinks and you aren’t able to fix it simply on your own, call the cooling experts at A&M Heating & Cooling LLC. We have years of experience working with a wide variety of HVAC systems. Our crew has fixed countless air conditioning troubles throughout the years—including strange smells. Call us today for quality AC repair in Tucson!