How does a Portable Air Conditioner work?

How does a portable air conditioner work? Air conditioners work “magically” and nobody ever fully gets them. As an electrical engineer, I try to break up the answer to this question into digestible chunks everybody can understand.

Quick answer: Like a regular air conditioner, a portable air conditioner cools the air by evaporating a refrigerant that carries the absorbed heat from your room outdoors. Since a portable air conditioner has no outdoor parts which ensure that no heat is carried back into the room, it is not as efficient as a regular air conditioner. 

Don’t worry if you do not understand the quick answer. We’re going to have a look at everything in a little more detail.

How does an Air Conditioner work?

To understand how a portable air conditioner works, we first have to look at regular air conditioners.

At the first glance, we see that air conditioners contain a duct system. These ducts contain a compressed refrigerant. Normally, this refrigerant is gaseous. But when it is compressed (under high pressure), the refrigerant becomes a liquid.

Engineer’s note: This is actually the case for any gas, not just the refrigerant. When you apply pressure to a gas, it becomes a liquid. The reason is that the individual gas atoms or molecules don’t have much wiggle room when they are under pressure, so they behave like a fluid. The same happens when you cool down a gas, by the way. The only difference between the special refrigerant gas and any other gas is that the refrigerant is designed to evaporate and liquidate at around room temperature.

So, we have a duct containing the compressed liquid refrigerant. In hot air, the refrigerant absorbs the heat and evaporates, and becomes gaseous (think: evaporated refrigerant contains heat energy).

Then, the evaporated refrigerant is led outside, to a compressor, which usually is attached to the outside wall of the house. The compressor compresses the gaseous refrigerant, which turns it into a liquid again. You can think of compressing as the reverse action of evaporation.

This means: The refrigerant becomes liquid again and releases heat.


  1. The refrigerant absorbs heat inside through evaporation and becomes gaseous. Think: In gaseous form, refrigerant carries heat energy.
  2. The refrigerant is pumped outdoors where a compressor compresses it and turns it into a liquid again. The refrigerant releases the absorbed heat outside through condensation

The process is cyclomatic. An AC needs electricity to power the compressor (to compress the refrigerant and release heat) and to power the fans which distribute the hot and cold air.

This air conditioning process cools down your room.

What’s the difference between a regular and a portable AC?

So, what exactly does a portable air conditioner do differently? Technically, there is no difference between a regular AC and a portable AC. Everything works precisely the same. At least when viewed on an abstract level.

The main difference between portable air conditioning and regular air conditioning is just the assembly of the device. 

While a regular air conditioner consists of separate, but connected components located inside and outside of a room, a portable air conditioner is a single device.

In a portable AC, all the parts, the ducts, the compressor, the fans, etc., are sitting inside one encasing. This makes the whole thing portable.

So, the difference between a regular and a portable air conditioner is not technical, but rather a design difference.

Nevertheless, a portable air conditioner still accomplishes the same task as a regular AC. It compresses a refrigerant, blows cold air into a room, and extracts heat from a room.

Portable air conditioner types

There are three types of portable air conditioners.

Portable air conditioners come in two variants:

  • Dual-hose portable AC: One hose for sucking in air from outdoors, which is then cooled in the AC system, and another hose for blowing hot air outdoors.
  • Single-hose portable AC: A single hose for blowing hot air outdoors
  • No-hose portable ACs: These are, in my honest opinion, a hoax. Portable air conditioners need a hose to expel the hot air outdoors. Portable air conditioners without a hose blow both cold and hot air into your room. Doesn’t make sense, right? No-hose portable ACs are a marketing scam and are just fancy fans.

The dual-hose portable ACs the most efficient of all three types. This means for the same amount of electricity cost, you get the highest cooling effect with a dual-hose portable air conditioner.

Dual-hoses do not need to suck any indoor air. One hose carries outdoor air into the device, which is then cooled. The other hose carries the excess heat outdoors. The Whynter ARC-14S portable air conditioner (click here to view it on amazon) is by far the best-rated portable air conditioner mainly because it uses a dual hose system and therefore works the best.

Single hose portable ACs, however, pull hot air from your room, cool it, exhaust the excess heat and blow the cool air back into your room. Since the AC sucks air from your room, your room is under negative pressure which causes hot air from other rooms to enter through the door gaps.

This significantly reduces the efficiency of single-hose portables when compared to dual-hoses.

No-hose portable air conditioners do not work at all. They might produce cool air. But where does the extracted heat go? Well. It goes right back into your room. Do not even think about buying a portable air conditioner without hoses. It won’t work.

Are regular or portable air conditioners more efficient?

In a portable air conditioner, all of the parts that would be separated across different locations in a regular air conditioner, are gathered close to each other inside one encasing.

Because all the parts sit closely together, there is heat exchange between them. And heat exchange between parts always reduces efficiency.

The parts extracting heat and the parts producing cold air are not in two separate devices as in a regular heater. This means the hot parts transfer a part of the heat back to the cold parts.

Aside from the insulation inside the portable air conditioner, portable air conditioners often come with cheaply made hoses. These also leak heat (either by heat passing through the thin material or even by actual air leaks), which reduces the efficiency a bit more.

And on top of that, the efficiency of a portable air conditioner depends on proper setup. A portable air conditioner can only be efficient when the hoses and the window kit are connected tightly and everything is sealed properly.

When to choose a portable over a regular air conditioner?

There is a reason why you see regular built-in air conditioners are the go-to choice for most homeowners. 

A regular air conditioner has higher efficiency. Everything is set up once. After that, the efficiency does not depend on how well you tighten hoses or how you place the AC. Also, a regular AC does not occupy any floor space.

However, built-in air conditioners come at a higher initial cost and furthermore additional maintenance costs.

A portable air conditioner, meanwhile, is quick to set up and is cheaper. Also, it’s portable and very easy to replace. A portable air conditioner can save you a lot of headaches. 

You should get a portable air conditioner if you want to save money, if you want to use your portable AC in multiple locations, or if you just don’t want to install a fixed system.

Personally, I say that you can get a great air conditioning experience as long as you set up your portable air conditioner correctly. Ensure you connect your portable air conditioner hoses tightly to the window kit. Also, make sure that there are no leaks and that everything is well-insulated. And I absolutely vouch for the dual-hose portable air conditioners. They are as close as you can get to the regular built-in AC experience.

A dual-hose portable AC is a great choice for quick and portable access to air conditioning.

For home use, to get the most out of your portable air conditioner, you should always consider maximizing the efficiency (here’s a guide on how to make a portable air conditioner more efficient).

In short, you should keep your room well insulated, windows and doors closed and you should seal all leaks in the ducts using HVAC tape.


Portable air conditioners work just the same as a regular air conditioners. The only difference is in the arrangement of parts. While a regular air conditioner consists of separate devices placed indoors and outdoors which are connected through ducts, a portable air conditioner is a single device, which you can move anywhere.

Portable space heaters are handy to use anywhere you desire air conditioning. However, they have lower efficiency when compared to a built-in system.