Why Does My Portable Air Conditioner Smell & What To Do?

Portable air conditioners, like any other type of air conditioner, can develop a bad odor, which will spread throughout your room. There are various types of odors, and you may need to address them in various ways.

In this post, I’ll go over all of the common smells in a portable air conditioner and how to get rid of them.

Simply put, most bad smells in a portable ac are caused by mold and bacteria in the machine and could be eliminated by a thorough cleaning. 

Why does your portable AC smell?

When people talk about the bad smell of a portable air conditioner, they’re probably not referring to the same smell. As a result, I’d like to investigate the source of each smell separately.

Portable AC smells musty

In nine out of ten cases, the smell emitted by a portable air conditioner is musty. This odor frequently indicates the presence of mold, mildew, or bacteria in the machine.

The dirty air filter can accumulate a thick layer of dust and dirt, as well as some moisture. This creates an ideal environment for the growth of these microbes.

Mold and mildew love to grow on a dirty evaporator coil. They can feed on the grime that has accumulated on the coil. They also require the moisture collected through condensation to grow.

A dirty coil can also cause it to ice up, increasing the humidity inside the machine even more. Mold thrives in damp environments, so you can expect the machine to emit a stronger musty odor in this situation.

Aside from that, stagnant water in the drain pan can produce a moldy odor. In addition, mold and mildew are likely to appear when the portable air conditioner leaks water.

Check here to understand why other types of ac have a musty smell.

Portable AC smells like pee

Your portable air conditioner may occasionally emit a urine odor. It does not imply that someone urinated in the machine. It’s because some molds and bacteria can produce Ammonium, which has a urine-like odor.

In exceptional circumstances, the rodent animal may enter the machine and relieve itself. Their feces and urine can emit this odor.

See also why other types of ac smell like pee.

Portable AC smells like rotten eggs

If your portable air conditioner smells like rotten eggs, you should act quickly. The smell is almost certainly caused by natural gas leaking in your home.

Another potential source is sewage gas from the plumbing system. When there is a crack in the pipe, it can leak into the room and into your portable air conditioner.

See also why other types of ac smell like rotten eggs.

Portable AC smells like vinegar 

The vinegar smell is similar to the musty smell, which also comes from the bacteria and mold inside your machine. The reason why it releases a sour odor, rather than a musty smell, is that the types of mold and bacteria are different. 

See also why other types of ac smell like vinegar.

Portable AC smells like fish

If you have a brand new portable ac, it is normal to see it emit a light plastic smell. Otherwise, the fishy smell is often caused by an overheating electrical component in your room or the ac itself.

When the electrical component is overheated, the plastic coating will burn, giving off a fishy and plastic smell.

See also why other types of ac smell like fish.

Portable AC smells sweet

All the smells I mentioned above are unpleasant odors. But your portable ac can also smell sweet. However, it indicates that there is a refrigerant leak. 

Refrigeration is hazardous to our health and will cause numerous respiratory problems.

See also why other types of ac smell like chemicals.

How to get the bad smell out of your portable air conditioner?

Since you understand why your portable smells, we can start exploring how to eliminate these foul smells.

Open the windows 

open window

Because we will be closing the windows while running an ac, you should open the windows if you notice any foul odors. This can help to dilute the harmful chemicals in the air, which is beneficial to your health.

When there is a gas leak, leave the house as soon as possible 

If your portable air conditioner smells like rotten eggs and you’re not sure if it’s due to a gas leak in your home, you should leave as soon as possible because natural gas is not only flammable but can also cause you to lose consciousness and die.

Notify the local fire department as well as the gas supplier. They will deal with the situation.

Clean the air filter 

clean ac filter

According to our previous discussion, the air filter and evaporator coil are common sources of bad odors. Cleaning the filter can sometimes solve the problem.

The air filter on a portable air conditioner is frequently located on the back. You can easily displace it with your hands. The simplest way to remove debris from it is to rinse it under running water. A brush is frequently useful in removing stubborn stains and grime.

After it has dried, replace it to see if the odor has been reduced.

Clean the evaporator coil

Cleaning an evaporator coil in a portable air conditioner can be difficult because you must disassemble the unit to expose it. As a result, if you insist on doing it yourself, you risk damaging your machine.

To clean it, blow away the debris on the surface with a can of compressed air. If the coil is too filthy, apply some coil cleaner and wait for a while for the buildup to dissolve.

Unclog the drain hose

If you choose to manually drain the water, place a shallow container beneath the drain spout and then open the spout to catch the water in the drain pan.

If your machine drains through a hose but still reminds you to drain the water, the hose is clogged. Hisense portable ac, for example, will display an E5 error code.

Fortunately, the drain hose can be removed. To remove the slime, use a brush on the wire. It’s also a good idea to replace it with a new hose.

Hire a pro

You may need to fix the leaks in the plumbing system or coils to remove the smell. There may be something wrong with the electrical system as well. 

These tasks need a certified technician to finish. They have the expertise and tools to locate the leak, test the refrigerant level, or diagnose why the appliance will become overheated.


If you notice your portable air conditioner smells, chances are the cause is mold and bacteria in the device. However, refrigerant leaks and natural gas leaks could also be to blame.

Cleaning the filter and evaporator coil can usually get rid of the odor. However, in some cases, you may require the assistance of a professional.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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