The Sniff Test: Why Your Air Conditioner Smells and How to Fix It

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

Depending on the cause of the odor, the culprit may be bacteria or fungus in the system. In other cases, it could also indicate something mechanically wrong with the AC. Some smells are a warning of a dangerous situation, including a natural gas leak.

At Knoechel Heating, we have a nose for these sorts of things. If you smell something odd coming from your air conditioner, chances are our team of talented professionals has smelled it, too—and fixed it! We’ve earned the reputation as the first call for air conditioning repair in Zelienople.

What does a specific odor billowing from your air conditioning mean? Here are several frequent air conditioner smells and what they could mean:

My Air Conditioner Smells Like Feet

If your air conditioner smells like feet, it might be due to a buildup of bacteria or fungus in the system. When moisture accumulates inside the unit, it can establish an environment that is favorable to the spread of bacteria and fungus. This can result in a nasty odor that is often described as smelling like feet.

Another possible reason for the stench of dirty feet could be a dirty air filter. When the air filter becomes filled with dirt, dust and other particles, it can result in substandard air quality and a musty smell that bears a resemblance to feet.

To fix this unpleasant situation, it's important to have a professional inspect and clean your air conditioning system, including the evaporator coil, drain pan and condensate drain line. It's also important to replace the air filter routinely to promote good air quality and protect against the formation of bacteria and fungus.

My Air Conditioner Smells Like Rotten Eggs

If your air conditioning unit reeks of rotten eggs, it could 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 a situation that 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 air out the area, make everyone leave the building and call your gas company or emergency services immediately.

My Air Conditioner Smells Like Mildew

If your AC is giving off an odor like mildew, it might be due to a collection of moisture inside the unit. When moisture forms inside the air conditioning system, it can promote the growth of mold and mildew. This can cause a musty stench that it similar to mildew.

Another possible reason for the smell might be a clogged air filter. Once the air filter becomes clogged, it can result in poor air quality and a musty smell that has a resemblance to mildew.

Routine air conditioning maintenance from Knoechel Heating can help avoid 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 scenarios is when your AC smells like urine.

If your air conditioning stinks like urine, it could be due to a variety of factors. One possible cause is a accumulation of bacteria or mold in the your HVAC. This can happen if moisture accumulates in the system and creates a wet environment that can promote bacterial growth. The bacteria can emit a foul odor that resembles urine.

Another possible 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 stopped up by debris, it can cause water to back up and accumulate inside the unit. This can create a musty smell that is sometimes described as smelling of urine.

My Air Conditioner Smells Like Burning Plastic

If your air conditioning system smells like burning plastic, it might be because of an electrical issue with the unit. After some time, the electrical elements in the air conditioning system can wear out or malfunction, which can produce a burning smell that resembles plastic.

Another possible root cause of the smell could be a foreign object stuck in the HVAC system. If something foreign gets caught in the air conditioning system, it can heat up and cause a smell that reminds people of burning plastic.

If you smell burning plastic coming from your air conditioner, it’s worthwhile to call 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 recognizable smell, often described as smelling of rotten eggs or sulfur. That’s because this scent is added to natural gas to make sure that it is easily detectable.

As we said previously, a natural gas leak can be VERY harmful and requires immediate attention. Should you suspect a gas leak, turn off your air conditioning system, open windows and doors to air out the home, leave the building and call your gas company or emergency services as soon as possible.

Why My Air Conditioner Smells Like Fish

When your AC smell like fish, it could be due to a build-up of bacteria or mold in the unit. Moisture produces 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 create a smell like dirty feet.

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

To correct the issue, it's often necessary to have a professional inspect and clean your HVAC system. They will be able to find the source of the smell and take the proper steps to remove any contaminants and prevent the problem from recurring.

Why My Air Conditioner Smells Like Vinegar

There could be multiple reasons an air conditioner smells like vinegar. One possible cause of the smell could be a clogged air filter. Another likely cause of the smell may be a refrigerant leak. Sometimes after the refrigerant leaks, it can create a chemical odor that is described as smelling of vinegar.

To fix the issue, it's essential to have a skilled tech examine and clean your air conditioning.  If the odor lingers after the cleaning and exchanging 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 mechanic can tell you if your air conditioning should be replaced.

If you are looking to upgrade, Knoechel Heating can help locate the correct unit to fit your home’s needs. We offer trustworthy, professional air conditioner installation in Zelienople.

My Air Conditioner Smells Like Chemicals

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

Another possible source of the smell could be something wrong with the electrical wiring or components inside the air conditioning system. This can produce a burning smell that resembles chemicals or burning plastic.

If you think your system has a refrigerant leak or an electrical concern, it's important to turn 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 prevent injury or damage to your home.

Strange Smell Coming from Your AC? Call the Pros at Knoechel Heating

If your air conditioner stinks and you aren’t able to fix it simply on your own, reach out to the cooling professionals at Knoechel Heating. We have lots of experience working with a wide variety of HVAC systems. Our crew has fixed countless air conditioning concerns through the years—including funky smells. Call us today for quality AC repair in Zelienople!