Do Portable Air Conditioners give off Carbon Monoxide?

Do portable air conditioners give off carbon monoxide? There are two reasons why many homeowners ask this question.

Quick answer: No, portable air conditioners do not give off carbon monoxide. Carbon monoxide is only created from fuel-burning devices such as furnaces, gas stoves, and generators. Portable ACs use electricity so there is no risk of them emitting carbon monoxide.

However, there are a few uncommon situations whereby your portable AC could be involved in circulating carbon monoxide in your home. Read on to learn the real culprits you should be worrying about.

Why People Think Portable Air Conditioners Emit Carbon Monoxide

If you haven’t seen a portable air conditioner up close, it has an exhaust hose on one side that goes outside the house through a window. The purpose of this hose is to expel the hot exhaust air and water vapor collected during the cooling process.

Steam leaving the portable AC’s hose

In certain conditions (air pressure, humidity, temperature, etc), the hot air can leave the hose in the form of a whitish smoky gas, similar to what your car exhaust or chimney produces.

This white gas is actually just steam and completely safe. When your room is very humid and outdoors it’s very cold, the emitted hot air condensates to tiny water droplets.

This is the number one reason why people think portable air conditioners emit harmful gases such as carbon monoxide.

But why does everyone worry about carbon monoxide specifically and not any other gas?

Carbon monoxide-awareness in the US

As I mentioned above, carbon monoxide is made by fuel-burning devices such as car engines, home heating systems, clothes dryers, power tools, boilers, gas stoves, and anything else that uses fuels.

As such, we are aware that many devices we use at home produce carbon monoxide. This is why furnaces have vents, gas stoves have a hood, and generators are used outside the house.

It’s only normal to imagine that your air conditioner works the same way as these other devices, especially when you see the smoke coming out of the hose. Also, when people hear that air conditioners use refrigerant (which is either gaseous or liquid) to carry the air around the AC, they imagine this gas is harmful or can leak into the house.

However, the refrigerant used in ACs is made of hydrofluorocarbons (HFCs), not fuel, and they are completely harmless. Second, there is no way this gas can leak out unless you drop the AC and damage the components, in which case it can’t work anymore.

Carbon monoxide is undetectable using just our senses

So let’s put this myth to rest once and for all. Carbon monoxide is an odorless, colorless, and non-irritating gas that’s very challenging to detect without special equipment. This means you can’t see or smell it, and that white smoke is not carbon monoxide.

The danger with carbon monoxide, besides being undetectable, is that it tricks your body into thinking you are receiving oxygen, so the body stops taking in oxygen. With time, carbon monoxide replaces all the oxygen in your body, and you pass out because of a lack of oxygen. If no help comes soon, death is inevitable and that’s how 400 Americans die from carbon monoxide poisoning in their own home every year.

It’s critical that you stay aware of any device emitting carbon monoxide into your environment and take the necessary precautions.

How a Portable Air Conditioner can increase Carbon Monoxide levels

A portable air conditioner on its own cannot produce or emit carbon monoxide or any other harmful gas. However, it can absorb or collect air with carbon monoxide and distribute it to the house.

Here’s how:

Indoor air circulation

A portable AC contains a duct system that has a compressed liquid refrigerant. When you power on the AC, it draws in hot air from your house and pushes it through the ducts where it’s absorbed by the refrigerant and evaporates, turning into gas.

This gas is pushed outside to the compressor, and the compressor turns the gaseous refrigerant containing hot air into a liquid again.

The liquid then releases the heat and the moisture through the exhaust hose and starts the journey back to the house with cold air only.

Now, if the air in your house has carbon monoxide already caused by your furnace, oven, or stove, the AC will absorb that air and return it back cold but still full of carbon monoxide.

That’s because the AC does not filter the air thoroughly enough to catch carbon monoxide. If you suspect carbon monoxide emission in your home, the best solution is an air purifier.

Powering a portable AC with a generator

While portable air conditioners use electricity for power, they can also be powered using a generator.

This is often useful for RV living or temporarily during construction work in the high summer heat.

A gas-powered generator can emit carbon monoxide even when it’s not malfunctioning. As a result, your AC will absorb this carbon monoxide and circulate it all over your space.

Portable air conditioner hoses allow carbon monoxide to enter the room

The last though unlikely way your AC can contribute to carbon monoxide circulation is through the exhaust hose.

This hose goes through the window to the outdoors or another room. Sometimes, if there are carbon monoxide-producing devices outdoors such as a generator, running vehicle, or charcoal grill, your hose might allow that carbon monoxide to enter.

The amount of carbon monoxide entering is usually minimal, but it’s still something to consider.

You should therefore be very mindful of where the vent goes and avoid exposing it to fuel-burning components nearby.

How to Ensure Your Portable Air Conditioner is Carbon Monoxide Free

To reiterate, a portable air conditioner does not produce carbon monoxide. However, it can draw in air that already contains carbon monoxide from the house or your outdoors through the vent. This air will then go through a cooling process and redistribute into your home.

You can avoid this unfortunate scenario in 3 ways;

Maintain your fuel-burning devices regularly.

If you have a gas furnace, oven, or stove, among others, keep up with the annual or bi-annual maintenance. 

You should hire a professional technician to come and check that everything is still in working order and that there are no leaks or clogs anywhere. This will also mean maintaining your heating system by cleaning the vents, changing the filters, and so on.

Keep outdoor fuel-burning devices away from the AC vent.

I get it; you want to grill meat near the kitchen and fix the car right in the garage. But sure however that your AC vent is nowhere near these places. The window used to vent out a portable conditioner should be very far from your generator, garage or grill. Also, don’t under any circumstances use a grill or generator inside the house, and always open the garage door when the car or motorcycle engine is running.

Install a carbon monoxide detector.

You should have a carbon monoxide detector at home. That’s a small device that detects critical levels of carbon monoxide and gives off an alarm.

This will not help prevent carbon monoxide production, but it will alert you when you have a problem.

Unfortunately, these detectors only go off when carbon monoxide levels are quite high. If you notice that you and other family members are complaining of headaches, chest pain, dizziness and nausea, especially during the cold season when the furnace is on, have the house and the entire family tested for carbon monoxide.

Do Portable Air Conditioners Emit Harmful Gases?

Carbon monoxide is not the only gas you should worry about when dealing with machines and appliances. Thankfully, portable air conditioners do not emit any harmful gas, unless it’s made of substandard materials.

For instance, some cheap portable air conditioners come with a poor plastic window kit that will produce Volatile Organic Compounds when subjected to heat. This is something to look out for as you compare the prices and qualities of portable air conditioners out there.

Besides quality, you also have to ensure the vent system is tight and well-secured. Poor quality vents have been known to come loose and leak the vapor and hot air into the house instead of taking them outside.

I find that cleaning the ACs vent, condenser, and evaporator coils also helps to prevent any stinky smell.

I recommend this AC clean brush set (click to view it on amazon) for the coil and air filter and also this evaporator coil cleaning foam (click to view it on amazon) to get rid of all the grime and dirt.

Never ever use water to clean the inside of an air conditioner because it will only cause mold and malfunction. Always dry-clean everything!

Go for high-quality portable ACs that are easy to clean. Too cheap portable air conditioners can be a health risk. And your health is expensive.


Portable ACs do not release carbon monoxide or other harmful gases. However, if the surrounding environment already has carbon monoxide, the AC may draw in that air and distribute it inside your home. It’s therefore important to ensure the air around your AC vent is clean and free of harmful compounds.