blonde woman wearing casual turtleneck sweater smelling something stinky

An air conditioner can be a handy tool in keeping your home cool and comfortable. But if your cool air is coming out with an unpleasant odor, you’ll want to look into getting that fixed as soon as possible.

There are a few different reasons your air conditioner could be emitting a vinegary smell. To stop the smell and fix your air conditioner, you first need to understand what is causing the unpleasant smell so you can remedy the situation.

Causes of Vinegar Odor

Mold and Bacteria

If your air conditioner isn’t expelling water quickly enough, it could result in mold or mildew growing inside of your air conditioner. Some types of molds have a scent that is similar to vinegar.

It is extremely dangerous to have a moldy air conditioner as mold spores are dispersed into the air. Breathing in mold spores is extremely harmful to your health, especially if you have young children in the home.

Electric Motor

If your air conditioner uses an electric motor, it may be emitting ozone that is causing the sour smell. Ozone is an inorganic molecule made up of three different oxygen atoms. It comes from electric power and is an emission that results from using electricity to create energy.

Ozone has a very unpleasant and distinctively pungent smell. If your air conditioner is producing too much ozone, this will cause a vinegary odor in addition to harmful toxins in the air that are bad for people to breathe in.

Excess Condensation

Cooling coils are the part of the air conditioner that adjusts the temperature of air that passes through. As air is sucked in and run over these cold coils, it lowers in temperature and then is pushed out to create a cooler space.

When this process occurs, condensation is created. Condensation is usually collected in a pan and drained out of the air conditioner or filtered back through to cool more air. But if too much condensation is produced, which could happen in an extremely humid atmosphere, the coils may begin to smell like vinegar.

Malfunctioning Filter

The air filter that cleanses the air as it comes in and goes out of the air conditioner can become broken. If this happens it may mean mold and other toxins in the air are being expelled through the air conditioner.

Clogged Condensation Pan

If the air conditioner has a condensation pan, it could easily become clogged from particles in the air. This isn’t common in normal houses but can occur in very dusty places like warehouses. Luckily, emptying the condensation pan is easy and usually just needs to be run under hot water to become unclogged.

If you allow the clogged pan to remain in the air conditioner, this can result in serious mold problems that will negatively affect your health.


Young Woman Checking Air Conditioner In House
Source: Shutterstock

Try these solutions before you throw away the air conditioner or call in a professional.

Clean or Change Air Filter

This is often the best way to fix your smelly air conditioner. The air filter traps all the toxins and harmful components in the air so you can breathe freely. Replacing or cleaning your filter is the first thing you should try to get rid of the vinegar odor.

Remove Moisture

If it turns out the filter isn’t the problem, try opening up the unit and drying it out. Use cloths or paper towels to soak up as much moisture as possible. The dampness is often the source of bad smells in air conditioners. Reducing the moisture in your AC unit is always a good idea, even if you aren’t experiencing a bad odor.

Clean the Vents

Cleaning the vents can remove any possible mold or mildew causing the smell. Use a brush and really get in there to retrieve any possible mold that is hiding. Using an anti-bacterial cleaning agent or bleach mixed with water is the best cleaning method.

Other Strange Smells

Vinegar is a common odor that comes from a faulty air conditioner, but other smells can haunt homeowners that just want a comfortable home. These are the most common odors that air conditioners emit that are a nuisance to people inhabiting the space.

To understand why these odors are occurring, you should familiarize yourself with the causes, so you’re prepared for a smelly air conditioner.

Dirty Laundry

If you know you did your laundry yesterday, but your room smells like smelly socks, it may be your air conditioner. This happens so often it has been dubbed “Dirty Sock Syndrome.” The cause is usually the air handler being covered in mold. This is especially true if the smell is not consistent but instead every once in a while.


The most common cause of a mildew smell is a clogged filter that needs to be cleaned or replaced. This could also mean the ductwork of your HVAC system is damp and could be growing mildew. This may sound obvious, but many people struggle to locate the source of these smells.


This one is particularly gross. If your air conditioning unit smells like rotten eggs whenever it is running, the cause is most likely a dead animal in the unit. Keep in mind a gas leak can also smell like rotten eggs, so this should be the first thing to consider when this scent arises.

Bottom Line

Don’t ignore the smell of vinegar coming from the air conditioner. It could be a sign of mold that may be affecting your health. Mold and mildew should not be taken lightly, so take the necessary steps to keep your air conditioner clean and running smoothly.

Don’t live with the nasty smell of vinegar in your home when you just want a comfortable space. Everyone deserves a quiet and clean-smelling air conditioner in their home.


What If My Car Air Conditioner Smells Like Vinegar?

The cause is likely mold. Spraying bleach mixed with water right into the vents is a great way to kill the mold. To be more thorough, you can scrub the car vents with a brush and cleaner.

What If None of This Works?

If none of the solutions in this piece get rid of the smell, it is likely too deep into the air conditioner for you to access and clean. You can try completely breaking down the unit, calling an HVAC specialist, or you may want to consider other possible sources of the odor.