El-Cheapo Portable AC Unit for the Office




My workplace is pretty hot, and all I have to help cool down during the day is a small 4" fan and an industrial blower system sucking hot air from the main building.

Tired of all the heat, I started to figure out a way of cooling myself at work the cheapest way possible.

So, here is a basic instructable on how to build a small AC unit that only cost me 4€.

You will need:

- Small aquarium water pump
- Radiator from fridge;
- Wire
- Paint
- Plastic tubing


- Plyer
- Metal shears
- Brass or soft steel brush

Step 1:

Find an old refrigerator, cooler, dehumidifier, etc, that you can take the rear radiator from.

Two coils (four rows of tubing) should be enough.

Cut the piece from the radiator, clean it up (inside with an air blower or some water and outside), bend it carefully lenghtwise in 2 or 3 and paint it.

Step 2:

Get an aquarium water pump and connect one piece of plastic tubing to the pump and the radiator.
Connect another piece of tubing to the radiator and leave it. This one is the discharge or return line.

Step 3: Finished!

Know all you need to do is get a plastic container, fill with water just enough to cover the pump and add lots of ice.
If you can, seal the container in blue foam or other insulator to keep the ice from melting too fast.

Turn the pump on, place a fan behind the radiator and enjoy your cheap AC unit!

Step 4:

Here is my setup.

It works best this way as the air isn't restricted by all the wires of the radiator, but is still nicely cooled. Ducting the setup (fan + radiator) inside some blue foam would increase efficiency even more!

Also, get the side where the water gets inside the radiator opposite the fan (facing you), and the exit side near the fan.

This way, the air is progressively cooled; if it was turned th other way round, the cold air would loose its chill by trying to cool the warmer water circulating near the end of the radiator.

You can see the cardboard is wet, especially on the coolest intake coil, due to condensation of moisture from the surrounding air on the two photos.

Step 5: How It Works?

The pump will circulate cool water through the radiator, which will cool the surrounding air; all the little fins and wires that compose the radiator increase the cold surface area.
One may expect some condensation on the radiator if the environment is hot and humid.



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    6 Discussions


    3 years ago on Introduction

    Not a bad idea at all... so much room for improvement! =]
    im taking this idea and putting it into a foam icebox with the fan forcing the cool air out and another radiator the is taking in the warm air and cooling it before moving on into the ice box to be recycled for the cooling air. hope that PC fans could do the trick because im planning on putting this in my car. Arizona heat with no AC in the car really sucks!


    Very cool...

    You could easily use a small lunch sized cooler to help with the ice situation and prevent spills. Although you will be pumping heat from the exchanger back into the ice anyway.

    Add salt to the water to drop the water temp a few more degrees without icing things up.

    2 replies

    Reply 6 years ago on Introduction

    The only problem with salt is corrosion, especially if the piping of the radiator is from steel, as is on my case. Copper tubing would be more resistant in that case.


    Reply 6 years ago on Introduction

    I doubt you would have a problem with corrosion in the lifetime of the unit. Another idea would be a closed system with rubbing alcohol and two exchangers. One for the fan side and one for the ice side. You would need a different pump than the aquarium pump.

    (or you could just use it the way you have it and enjoy. 8D)

    Depending on how compact one builds, yes, it doesn't take much room, and is very helpful.

    Thank you Penelope :-)