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Does portable AC bring fresh air?

Portable ACs can be fascinating devices. No doubt you’ve noticed the gigantic tube you attached to your window. You may wonder if it’s bringing outdoor air into your home. 

Does portable AC bring fresh air?

No, portable AC doesn’t bring fresh air. A portable air conditioner works by removing heat from the air inside your home and blowing it outside via an exhaust tube. It doesn’t create fresh air or filter air in your home.

You may think that the tube that connects a portable air conditioner to your window is sucking in air from the outside. But it’s not. That tube is the exhaust tube and pushes hot air out of your window.

The best way to think about how a portable air conditioner works is that it’s not cooling your home’s air. Instead, it is sucking heat out of your apartment and blowing it outside.

How this works is a little complicated. We’ve done a whole article on it if you want to understand the whole process.

Basically, a chemical called refrigerant (similar to antifreeze in your car) absorbs heat from your indoor air and then transfers it to the outdoor air. A motor in your portable AC uses pressure to change the relative temperature of the refrigerant in order to make this happen.

Your portable air conditioner is actually split into two for this purpose, with a partition between the two sections. One half contains all the elements that suck heat out or your home’s air (the cold side). The other has all the components that dump that hot air outdoors (the hot side).

So if a portable air conditioner actually pushes air out of my apartment rather than bringing any in, won’t my apartment lose all its air?

That would happen if there weren’t tiny sources of outdoor air dotted all around your apartment. While the portable air conditioner isn’t pulling any air into the room, it does lower your apartment’s air pressure.

That means other air is pulled into your home, from under the door and through cracks in your window pains.