When your air conditioner starts spewing strange or gross smells, it is necessary to take notice because it could be a sign of a big problem. Disregarding unpleasant smells coming from your air conditioning may lead to further damage to your HVAC system or even pose a risk to your health and safety.

Depending on what you're smelling, the culprit may be bacteria or fungus in the system. On the other hand, it could also sign something mechanically wrong with the AC. Some smells are a sign of an unsafe situation, such as a natural gas leak.

At Contra Costa Heating & AC, we are experienced at getting to the root cause of stinky smells. If you smell something odd coming from your cooling system, you can bet that our team of qualified specialists has smelled it, too—and fixed it! We’ve earned a reputation as the first call for air conditioning repair in The Bay Area.

What does a certain smell billowing from your cooling system mean? Here are a few common air conditioner smells and what they might mean:

The Air Conditioning Smells Like Feet

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

Another likely reason for an odor of stinky feet might be a dirty air filter. When the air filter becomes choked with dirt, dust and other contaminants, it can result in poor air quality and a musty smell that it similar to the smell of feet.

To correct this dilemma, 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 replace the air filter routinely to ensure good air quality and restrict the development of bacteria and fungus.

My Air Conditioner Smells Like Rotten Eggs

If your air conditioning equipment stinks like rotten eggs, it could be due to 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, which 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 at once.

Your AC Smells Like Mildew

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

Another possible reason for the smell could 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 Contra Costa Heating & AC can help protect against both of these situations, 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 undesirable things is when your AC smells like urine.

If your air conditioning reeks of urine, it could be due to a variety of factors. One likely cause is a buildup of bacteria or mold in the your cooling system. This can happen when moisture accumulates in the system and creates a damp environment that is conducive to bacterial growth. The bacteria can create a foul odor that some people describe as smelling like 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 correctly, but if the drain line becomes filled with debris, it can cause water to back up and accumulate inside the unit. This can produce a musty smell that resembles urine.

Your AC Smells Like Burning Plastic

If your air conditioner smells like burning plastic, a possible cause could be an electrical concern with the unit. After some time, the electrical components in the air conditioning system can wear out or bust, which can produce a burning smell that resembles plastic.

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

If you think you smell burning plastic coming from your cooling system, it’s worthwhile to contact a professional right away.

The Air Conditioning Smells Like Gas

If your air conditioning smells like gas, it could be due to a natural gas leak in the unit or in your home. Natural gas has a distinct aroma, often described as smelling of rotten eggs or sulfur. That’s because a smell is incorporated into natural gas so that it is easily detectable.

As mentioned before, a natural gas leak can be VERY dangerous and needs immediate attention. Should you suspect a gas leak, turn off your air conditioning system, open windows and doors to air out the home, evacuate the building and phone your gas company or emergency services straight away.

Your AC Smells Like Fish

If your AC smell like fish, this could be a sign of a build-up of bacteria or mold in the unit. Moisture causes an environment that fosters the growth of bacteria and mold. This can cause a disgusting odor that is often described as smelling like fish or, as mentioned earlier, it also can create a smell like dirty feet.

Another potential cause of the smell could be a dead animal or other biological material trapped within 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 solve the issue, it's often necessary to have a professional examine and clean your HVAC system. They should be able to identify the source of the smell and take the correct steps to remove any contaminants and stop the problem from recurring.

The Air Conditioning Smells Like Vinegar

There could be numerous reasons a home's air conditioning system smells like vinegar. One possible cause is a dirty air filter. A second possible cause of the smell might be a refrigerant leak. If the refrigerant leaks, it can generate a chemical odor that is described as smelling of vinegar.

To fix the issue, it's important to have a skilled specialist 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 tech can tell you if your air conditioning should be replaced.

If you are looking to upgrade, Contra Costa Heating & AC can help find the correct unit to fit your home’s needs. We deliver dependable, skilled air conditioner installation in The Bay Area.

My Air Conditioner Smells Like Chemicals

If the smell of chemicals is coming from your air conditioning unit, it could be caused by a refrigerant leak. If the refrigerant leaks, it can create a chemical odor that is often described as smelling like chemicals or paint thinner, vinegar or acetone.

Another possible reason for the smell could be problems with the electrical wiring or elements inside the air conditioning system. This can produce a burning smell that is like chemicals or burning plastic.

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

Weird Smells Coming from the Air Conditioning? Call the Pros at Contra Costa Heating & AC

If your air conditioner reeks and you aren’t able to fix it smoothly on your own, call the cooling specialists at Contra Costa Heating & AC. We have years of experience working with a wide variety of cooling systems. Our crew has fixed a multitude of air conditioning troubles through the years—including strange smells. Call us today for quality AC repair in The Bay Area!