When your air conditioner starts spewing unusual or funky aromas, it is necessary to take notice because it could be a sign of a major problem. Dismissing unpleasant smells coming from your cooling system can lead to serious damage to your AC or even pose a risk to your health and safety.

Depending on the smell, the cause could 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 a harmful scenario, like a natural gas leak.

At Contra Costa Heating & AC, we are skilled at diagnosing and fixing these type of problems. If you smell something odd coming from your air conditioner, you can bet that our team of skilled pros 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 some common air conditioner aromas and what they may mean:

My Air Conditioner Smells Like Feet

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

Another potential explanation for the stench of dirty feet might be a dirty air filter. If an air filter becomes filled with dirt, dust and other debris, it can lead to substandard air quality and a musty smell that bears a resemblance to feet.

To fix this issue, 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 replace the air filter on a regular basis 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 equipment smells like rotten eggs, it could be the result of a natural gas leak in the unit or in the surrounding area. Natural gas has a distinctive odor, often described as smelling like rotten eggs or sulfur, which is because of a substance added to it to make it easily detectable.

A natural gas leak is a situation that is extraordinarily 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, evacuate the building and call your gas company or emergency services at once.

My Air Conditioner Smells Like Mildew

If your air conditioner is giving off an odor like mildew, it might be due to a collection 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 cause of the smell could be a dirty air filter. When the air filter becomes clogged, it can cause poor air quality and a musty smell that resembles mildew.

Routine air conditioning maintenance from Contra Costa Heating & AC can help protect against both of these problems, 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 unpleasant things is when your AC smells like urine.

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

Another feasible 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 build up inside the unit. This can produce a musty smell that resembles urine.

My Air Conditioner Smells Like Burning Plastic

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

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

If you think you smell burning plastic coming from your AC unit, it’s worthwhile to contact 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 your home. Natural gas has a recognizable smell, often described as smelling of rotten eggs or sulfur. That’s because this scent is incorporated into natural gas so that it is easily detectable.

As mentioned previously, 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 call your gas company or emergency services straight away.

Why My Air Conditioner Smells Like Fish

If your air conditioner smell like fish, you may have a situation where there's a build-up of bacteria or mold in the unit. Moisture produces an environment that fosters the growth of bacteria and mold. This can cause a strong odor that is often described as smelling like fish or, as mentioned earlier, it also can result in a smell like dirty feet.

Another potential 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 gets trapped inside the unit and dies.

To correct the issue, it's worthwhile to have a professional examine and clean your HVAC system. They will 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 several reasons your air conditioning system smells like vinegar. One possible cause might be a clogged air filter. One other potential cause of the smell may be a refrigerant leak. If the refrigerant leaks, it can create a chemical odor that is similar to vinegar.

To fix the issue, it's essential to have a skilled specialist look at and clean your air conditioning.  If the odor persists after the cleaning and exchanging the air filter, it's best to reach back out to a professional to diagnose and repair any persistent issues with your air conditioning. Or, they can tell you if your air conditioning ought to be replaced.

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

My Air Conditioner Smells Like Chemicals

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

One other possible cause of the smell could be something wrong with the electrical wiring or parts inside the air conditioning system. This can result in a burning smell that it similar to chemicals or burning plastic.

If you believe there is a refrigerant leak or an electrical issue, 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 harmful and may require immediate attention to avoid injury or damage to your house.

Strange Smell Coming from Your AC? Call the Pros at Contra Costa Heating & AC

If your air conditioner stinks and you aren’t able to fix it simply on your own, contact the cooling specialists at Contra Costa Heating & AC. We have plenty 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 The Bay Area!