Why does my ac smells like fish? [Detailed Answer]

A common question most air conditioner users have is why does my aircon smells like fish when turn on.

This question arises so often because this problem is too common and nobody likes to have a stinky aircon, especially when they are expecting some relaxed and peaceful moment, the unpleasant smell coming from aircon completely ruins the mood and not only this but it is also bad for your health as well.

You probably are not aware of this, but ac smells like fish can cause several allergies, respiratory infections, and even asthma, so one thing for sure even if you are somehow comfortable with the unpleasant smell by the use of some air fragrance or room freshener, still it is too harmful to be left without solving the issue. This guide we will show you 8 possible reasons that cause aircon smells fishy and how to get rid of fishy smell from aircon.

The foul and pungent smell is caused by several internal and external factors, it is a bit difficult to figure out the exact source of bad odor, but we will be providing you some most common reasons which you can look out to get rid of aircon smell.

Mold and mildew

how to use Mold and mildew to fix air conditioner smelling problem

Even though there can be various reasons behind the foul smell of your aircon, the most common problem which is being faced at the time of maintenance is mold and mildew. The moisture and the excess of humidity inside your air conditioner are responsible for the formation of mold and mildew. There is a way to figure out if the fungus has started to grow in your air conditioner; if it starts to smell like a moldy odor, then it means your air conditioner system is too damp and moist, which is an adequate condition for organisms to grow and multiply.

To prevent this problem, which may even cause some serious health issues, you can do several things such as fixing all the water leaks inside your air conditioner and treating it with chemicals as it is necessary to destroy the fungus growing. Besides this, it is always a good idea to call a trained technician as they know best how to improve the air quality.

How to fix: Tilex Mold and Mildew Remover Spray can help you remove mold from your air conditioners. This product have 800+ five stars rating in amazon.

Cigarette smoke

If someone has been smoking cigarettes in your home or office and you are getting the smell of nicotine even if a cigarette is no longer burning, then it is because the smoke of the cigarette has reached the evaporating coils passing through the filters and this is responsible for the strong smell of nicotine you are getting.

How to fix: You can get rid of this issue by getting a maintenance service from an air conditioner expert, or if you can do it by yourself, you will have to change the aircon filter.

Animal waste and mold in ducts

As you know, air conditioners are mostly not used in the time of winter, and this is the time when birds and different kinds of rodents such as squirrels, mice, etc. make the air ducts their shelter. This sounds like a good thing, but the problem is that it may cause a pungent smell such as rotten eggs or rotten carcass when you finally turn on your air conditioner; this smell is mostly caused by the feces and urine of these animals. Another issue with them is that they can do damage to the wiring and ducts, this can also cause mold growing inside your duct, and it can cause a foul smell, which may even spread and multiply.

How to fix: You will have to remove the ducts and clean them on a regular basis, or you can contact professionals to inspect your duct and fix it.


Have you ever got a strong, stinking smell of rotten eggs when you turn on the air conditioner? If yes, then that means there is a leakage issue as there is a chemical name Mercaptan in the air conditioner and when the natural gas, which is basically odorless, combined with this chemical, causes this unpleasant smell.

How to fix: If you encounter this problem, then, first of all, turn off your air conditioner, and then you will require the help of a professional to do the work of cleaning and repairing.

Dry p trap

If there is a dry p trap, then you will have to face the sewer odor, which will refuse to go away and to make it go, you will have to contact an air conditioner expert to do the cleaning of the aircon system, and in case it is not because of dry p trap then it is probably backed up sewer or broken sewer vent pipe and to fix this you will need a plumber.

Clogged air conditioner and drain pans

Are you experiencing a strong and stinky smell that resembles wet carpet smell or smelly feet?

Well, this is because of clogged drain pans and to get rid of this smell you must clean your evaporator coils, or you should contact professional service to unclog the condensate drain pans as soon as possible because besides causing this foul smell if the filters are clogged, then the device might freeze as the air conditioner will not work properly, it can cause several other issues such as a heating pump or breaking the compressor of your air conditioner.

Rotting body of bird or rodent

When the dead body of an animal decomposes, it produces several chemicals which has a strong putrid smell. So, if your air-con is releasing this putrid smell, that means it probably has an animal carcass inside.

How to fix: In this case, the best option is to contact the pest management service or your maintenance provider.

Overheating parts

If you get the smell like gun powder or burnt plastic when you are using your aircon, then it means that there is some issue of overheating. In this case, first of all, turn off your air conditioner and check for wiring issues as it is easy to notice, but if you do not find any fault in wires, then you should call an aircon professional right away.

Now you know about the reasons why your aircon smell. So, if your air conditioner begins to emit a bad odor, then try to figure out the possible reason for this foul smell. After this, if you know how to fix it, then it is great, but if you don’t, then we suggest contacting a trained and qualified professional.

You may also interested to know what is dirty sock syndrome in an air conditioner and why does my aircon smell like vinegar.

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