When your air conditioner starts putting out strange or gross smells, it is a good idea to take notice because it could be a sign of a big problem. Ignoring unpleasant smells coming from your cooling system can lead to further damage to your air conditioning or even pose a risk to your health and safety.

Depending on what you're smelling, the cause might be bacteria or fungus in the system. In other cases, it could also sign something mechanically wrong with the AC. Some smells are a sign of a dangerous situation, like a natural gas leak.

At 1st Choice Heating & Air Conditioning, we are skilled at diagnosing and fixing these type of problems. If you smell something odd coming from your AC, you can bet that our team of talented specialists has smelled it, too—and fixed it! We’ve earned our reputation as the go-to team for air conditioning repair in Lake Forest.

What does a certain smell billowing out of your AC mean? Here are several typical air conditioner odors and what they may mean:

My Air Conditioner Smells Like Feet

If your air conditioner smells like feet, it may be because of a buildup of bacteria or fungus in the unit. When moisture builds inside the unit, it can create an environment that is beneficial to the growth of bacteria and fungus. This can result in a nasty odor that is often described as smelling like dirty feet.

Another possible reason for an odor of stinky feet might be a dirty air filter. If an air filter becomes clogged with dirt, dust and other contaminants, it can result in substandard air quality and a musty smell that resembles feet.

To fix this problem, it's important to have a quality service tech inspect and clean your air conditioning system, including the evaporator coil, drain pan and condensate drain line. It's also important to change the air filter regularly to ensure good air quality and protect against the growth of bacteria and fungus.

My Air Conditioner Smells Like Rotten Eggs

If your air conditioning unit reeks of rotten eggs, it could be caused by 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 can be extraordinarily 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, get everyone out of 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 may be due to a buildup of moisture inside the unit. When moisture collects inside a cooling system, it can foster the growth of mold and mildew. This can cause a musty stench that bears a resemblance to mildew.

Another possible reason for the smell could be a clogged air filter. When the air filter becomes clogged, it can result in poor air quality and a musty smell that is similar to mildew.

Annual air conditioning maintenance from 1st Choice Heating & Air Conditioning can help prevent both of these issues, because a good cleaning, inspection and filter change is a terrific way to keep your system operating at its best!

My Air Conditioner Smells Like Urine

One of the most unpleasant things is when an air conditioner smells like urine.

If your air conditioning reeks of urine, it could be due to a variety of factors. One likely cause is a accumulation of bacteria or mold in the your HVAC. This can happen when moisture accumulates in the system and creates a wet environment that is conducive to bacterial growth. The bacteria can produce a foul odor that it similar to urine.

Another potential cause of the scent of urine could be a clogged drain line. The condensation that forms inside the air conditioning unit needs to drain away properly, but if the drain line becomes filled with debris, it can cause water to back up and collect inside the unit. This can create a musty smell that can stink like urine.

My Air Conditioner Smells Like Burning Plastic

If your air conditioning unit smells like burning plastic, it might be because of an electrical problem with the unit. Over time, the electrical components in the air conditioning system can wear out or break, which can make a burning smell that resembles plastic.

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

If you notice something that smells like burning plastic coming from your AC unit, it’s worthwhile to phone a professional right away.

My Air Conditioner Smells Like Gas

If your AC smells like gas, there could be a natural gas leak in the unit or in the surrounding area. Natural gas has a recognizable smell, often described as smelling like rotten eggs or sulfur. That’s because an odor is put into natural gas to make it easily detectable.

As mentioned previously, a natural gas leak can be VERY dangerous and needs immediate attention. When you suspect a gas leak, turn off your air conditioning system, open windows and doors to air out the home, leave the building and phone your gas company or emergency services as soon as possible.

Why My Air Conditioner Smells Like Fish

When your air conditioner smell like fish, this could be a sign of a build-up of bacteria or mold in the unit. Moisture creates an environment that fosters the growth of bacteria and mold. This can cause a foul odor that is sometimes described as smelling like fish or, as mentioned earlier, it also can create 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 can take place if an animal such as a mouse or bird becomes trapped inside the unit and dies.

To solve the issue, it's important to have a professional inspect and clean your HVAC system. They will be able to determine the source of the smell and take the appropriate steps to remove any contaminants and stop the problem from recurring.

Why My Air Conditioner Smells Like Vinegar

There could be numerous reasons an air conditioner smells like vinegar. One possible cause is a dirty air filter. Another possible cause of the smell may be a refrigerant leak. Sometimes after the refrigerant leaks, it can make a chemical odor that is similar to vinegar.

To fix the issue, it's important to have a skilled mechanic inspect and clean your air conditioning.  If the odor lingers after the cleaning and changing of the air filter, it's best to reach back out to a professional to diagnose and repair any underlying issues with your air conditioning. Or, the tech can tell you if your air conditioning should be replaced.

If you are looking to upgrade, 1st Choice Heating & Air Conditioning can help select the right unit to fit your home’s needs. We offer trustworthy, skilled air conditioner installation in Lake Forest.

My Air Conditioner Smells Like Chemicals

If the smell of chemicals is emitting out of your air conditioning unit, it could be the result of a refrigerant leak. If the refrigerant leaks, it can create a chemical odor that people sometimes describe as smelling like chemicals or paint thinner, vinegar or acetone.

An additional possible cause of the smell could be problems with the electrical wiring or hardware inside the air conditioning system. This can cause a burning smell that it similar to chemicals or burning plastic.

If you suspect a refrigerant leak or an electrical problem, it's important to shut off your air conditioning system as soon as possible and contact a professional to inspect and repair the unit. Refrigerant leaks can be hazardous and may require immediate attention to avoid injury or damage to your house.

Strange Smell Coming from Your AC? Call the Pros at 1st Choice Heating & Air Conditioning

If your air conditioner smells nasty and you aren’t able to fix it smoothly on your own, contact the cooling experts at 1st Choice Heating & Air Conditioning. We have years of experience working with a wide variety of cooling systems. Our crew has fixed many air conditioning problems through the years—including funky smells. Call us today for quality AC repair in Lake Forest!