Skip to Main Content

Why DIY Air Conditioners Are (Mostly) a Waste of Effort

Can a bowl of ice and a fan really lower the temperature in your living room? No.
We may earn a commission from links on this page.
DIY air conditioner using frozen water bottles and a fan.
Credit: BOKEH STOCK - Shutterstock

Is it possible to make a useable air conditioner from spare parts? Whether climate change will ultimately end all human life on this planet or not is an open question, but seemingly no matter where you live, it’s hotter than ever this summer. If you have air conditioning in your home, that means figuring out how to make it work better and more efficiently.

But if you don’t have any AC at all, desperate times are leading hot people to making their own air conditioners. There are plenty of “DIY” instructional videos out there purporting to show you how to build a workable AC from a few relatively cheap components. But do any of them actually work?

How do you make your own air conditioner?

A typical DIY AC setup involves a foam cooler, some ice, some PVC pipe, and an electric fan. The idea is that if you’re moderately handy, you can throw together a survival cooling solution without spending much money. Ice is cheap, after all, and although electricity is expensive, a small fan won’t use much. However, these projects rely on water evaporation, and they’re not heat pumps—they simply cool air and then blow it around the room. So the answer to “do they work” is a frustrating “sort of.”


Supplies needed to build an easy homemade air conditioner


Different kinds of do-it-yourself air conditioners

There are many different ways to make DIY air conditioners, ranging from delightful milk carton models that act as personal coolers to more complex models involving small water pumps. Some of these require a small grasp of engineering or the ability to solder wire without injuring yourself. For those of us who regularly spend several minutes puzzling over how to insert a USB cable, one of the easier approaches is the foam-cooler-and-small-AC-powered-fan concept (large buckets can work just as well), which requires some power tools but no real expertise in, well, anything aside from plugging things into your wall.

All of these DIY ACs rely on the same principle: Cool air using ice, then blow that air through a tube of some sort. In theory, you can see how this should work: When you pack a cooler full of ice and beer and head for the beach, the air in that cooler is noticeably cold every time you open it up, even if the sun is blazing down. It stands to reason that if you could pump that cool air out of the cooler into your room, it would have at least some effect on the ambient temperature.

Do homemade air conditioners actually work?

Will a contraption like this make a noticeable dent in the room temperature? Not much of one. For a well-built DIY AC unit made from a cooler or a large bucket, you might get 1-2 degrees cooling for a very, very short time. One reason a beer cooler works is because it has a small, air-sealed space to cool down. Moving cool air out of the cooler constantly means the ice has to melt and transfer more heat energy into itself to compensate, leaving you very quickly with a puddle of water and a room that doesn’t feel much cooler. People sometimes think it’s working just because they can feel cold air coming out, but if it doesn’t budge the thermostat, it’s just an illusion.

On the other hand, as a close-up personal cooler? These will work. There will be a steady stream of cool air being concentrated into a tube and blown in your direction, and a DIY AC might drop the temperature in its immediate vicinity 10-20 degrees, which is noticeably cooler. That means that having one relatively close to you will offer some relief from the heat—essentially you’re building a kind of super-fan that blows slightly colder air onto you. It won’t change the overall temperature of your room, but it could make sitting in that sweatbox a little more tolerable, for a little while.

The reason window air conditioners and central air systems are so expensive is due to the fact that shifting heat from one space (your torturously hot bedroom) to another (the outdoors, where it becomes nature’s problem) requires a lot of power. Some ice and a small fan are just never going to do the same job—but it might help you hold onto the fraying ends of your sanity next time a heat wave drags through the area. Considering you can build one for less than $50, it might be a worthwhile experiment.

Five inexpensive air conditioners and evaporative coolers

Or you could put that $50 toward one of the coolers below and save yourself the trouble. Some ever have LED lights. I can’t personally speak for how well these work, but they all have better than 4 stars on Amazon with over 100 user reviewers.