Hacked AC Window Unit Split In Half To Cool The Garage

It’s getting into the hot summer months for those of us in the Northern Hemisphere, and for many Hackaday readers, that means its time to get the old window air conditioner out of storage and lug it back into position. But what if you’re trying to cool a space that doesn’t have a convenient window? In that case, this clever conversion that [Infrared] came up with to keep his garage cool might be of interest.

Basically, he’s taken the classic window AC and turned it into an impromptu ductless unit. By rotating the evaporator coils into a vertical position and lengthening the compressor wires, he was able to make the center of the AC thin enough that he could close his garage door over it. The back of the unit looks largely untouched, but the front side has a real Mad Max vibe going on; with sheet metal, exposed wiring, and a couple of fans thrown in for good measure. Fine for the garage or workspace, but probably not a great choice for the kid’s room.

[Infrared] says the hacked up AC can get his garage 18 degrees cooler than the outside air temperature in its current form, but he hopes the addition of some high CFM computer fans will not only improve performance, but let him make the new front panel look a bit neater. Though even in its current form, this is far from the most ridiculous DIY AC project we’ve seen in recent memory.

34 thoughts on “Hacked AC Window Unit Split In Half To Cool The Garage

  1. It would be even better if he converted the unit into a water chiller, and then the water/glycol cooling loop would be easy to diy into almost any configuration, including multiple fan coils from a single compressor.
    I cant find a single instance of someone making a chiller this way other than for aquarium chilling, and chillers for aircon use are very expensive, so a diy solution should make sense.

      1. Yes, it will. If the coils get below the dew point in the room, then ambient water will condense on the coils, regardless of whether the coils are full of refrigerant or water/glycol.

      2. Humidity will condense if the coils are cold enough. Split units have a dedicated ‘condensation’ pipe to the outside. Similarly, fan coils need to collect or direct condensate.

        Or, the best solution to this I’ve see recently, is to use the chilled water in an indoor ‘waterwall’ waterfall or fountain. The condensate collects directly on the chilled water.

    1. This is the basis for hydronic cooling systems, there are a number of commercial installations and increasingly some residential. They can be used with both air handlers and other radiant cooling systems including cooling panels. An upside (other than greatly increased efficiency from the high heat capacity of water vs air) is the ability to include thermal storage for time of use rate electricity shifting. An ice bank can be charged during off-peak hours and used instead of the chiller during high cost peak hours. The chillers condenser can also be used for domestic hot water pre-heating.

  2. Wonder how efficient the heat exchange would be if you just bathed the evap radiator in water, agitated it with the return inflow and pumped it round a loop. High surface area gas to water heat exchanger? Guess you’d have to run it through radiators again wherever you wanted coolness. Wonder if the inefficiencies stack up with each transition to the point where it’s not worth it.

  3. It’s almost a DIY mini-split (no heat), but *much* cheaper. That said, mounting a window unit in the wall is probably a better option if you own the property. The condenser will eventually fail because of corrosion (Al & Cu w/ H2O don’t play well together). I have a pair of 24,000 BTU window units that lost the refrigerant because of corrosion after only a few years of use. I’ll probably strip the compressors and junk the rest, though not sure what I’ll do with the compressors. Tough decision.

  4. I respect this simple hack. While it may not be complex and pretty, it gets the job done using what’s on-hand. I bet the OP would prefer to have a commercial A/C unit in his garage, but has reasons that isn’t possible. So rather than give up and sit on the couch, he took what he had and solved his problem to his own satisfaction. I like that. Kudos, Infrared!!

  5. If that was the case I’d tough it out personally. However here in the Midwest of the Americas we often see 40c with 90% humidity. That’s often why you see ac in a garage or workshop.

    Winter is anywhere from 0 to – 20 c

    The weather swing here is crazy

  6. I don’t think you’re quite over-smug and condescending enough. Try to be more insulting in the future, it’ll help.

    Doing work in a garage is a thing in nearly every country in the world. Not sure what you’re getting at.

    Besides, Eventually the garage heats up to match the environment. So what you actually mean is the 24-hour average temperature doesn’t go above 30c around your garage. Good for you! That’s great, it’s a nice pretty comfortable environment you have there. But some places it actually gets, you know, hot.

    For large portions of the US, 30c daytime temp ain’t hot. At all. My high today, coincidently, is exactly 30c. It’s the lowest high in the forecast. I doubt the house will go over 22 at any point during the day, thanks to in part to a meter of insulation in the attic and the concrete walls. So the AC won’t be running. Cuz it’s for when it gets hot.

  7. I can’t comment on the featured garage, but here the dew point on bad days will approach the typical maximum temperature of your garage. I run my window mounted garage AC not for temperature control but for moisture removal when I’m working on projects.

    1. This is exactly why I am doing it. The dew point today is 79. Egggh! But it works so well even with nothing blocking the gap under the door. I’m thinking like others have suggested, pool noodles to close the gap and maybe some foam board to go into the door sections. Also I have made some ducting out of flex dryer vent to help direct the cool where I am working.

  8. Last summer as a test I took a old window unit and some Foam sheets and exhausted the hot air from the compressor IE the part that sticks out the window and funneled it into the Attic access in the garage. It worked alright in the mornings and evenings but didn’t work very well during the mid day hours.
    I did this as a test for a possible portable A/C for the Garage but I ended up saving for a true air splitter.

  9. I would keep an eye out for an electric radiator or condensor fan for a car. Stretch the frame if the ac further so air can flow across the coils better and either push or pull the cold air into the room. The squirrel cage is prob working its arse off to run air through the enclosed box the coil is in. Give about 4 inches between the coil and garage door and ill bet it cools pretty well. I used an old rv unit to freeze out a big room in a boat house. 15′ ceiling 25 x30 room added insulation and paneled over it. Cut a hole about 24″ wide and 15″ tall. Put a shelf outside on the wall for tge unit to sit. And put on a parka cause itll freeze you out when its over 10p outside. The great thing about the rv units is no freon to deal with.

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