Portable 12V Air Conditioner --Cheap and easy!

This project is my dad's $10 solution to a $500 solution to a $25,000 problem. As I have previously mentioned around the site, my Dad owns an electric 1979 Ford Courier pickup, and is cool enough to let me drive it around. We absolutely love it, and wouldn't trade it for a Tesla Roadster, but one of the few problems with electric cars is heating and cooling. In a gas car, heat is provided by the 80% of the gas that is wasted as heat, and air conditioning is provided by a crankshaft-driven compressor system. Many EVs use hair dryer elements and fans for heat, and some, ours included, feature a powerful gasoline-burning heater.

(Update from 4-22-08: I'd forgotten that I mentioned the gas heater on here. Last fall the gas tank and heater were removed, and a ceramic heater was built in. It works great, although not quite as fast, and doesn't use gas.)

However, air conditioning is trickier because the shaft of an electric motor doesn't always spin. Some have used a compressor driven by the motor shaft anyway, while others have turned a compressor using a separate motor. Finally, my dad came up with part of the concept for this system. It pumps ice water through an evaporator core, which has fans that blow air through it. It is very simple, but we found what we were looking for at Sporty's Pilot Shop. They sell air conditioners built into ice chests for prices ranging from $475 for a basic model to $625 for a 24V, dual fan model.There is also an ArcticAir unit for $4750 with a full compressor unit. However, we like our $10 version better. I saw the ArcticAir display at EAA AirVenture Oshkosh this summer, and our unit is more compact and puts out cooler air. All you need is materials, basic construction/assembly and wiring skills, and a bag of ice. Let's go!

Update, 5-12-08: 100,003 views! Yay! I'm no Kipkay, but I'm still proud.

Step 1 Background and How it Works

This project is very similar to the ArcticAir Package Unit. In fact, I attached two pictures of it I took at AirVenture this past summer. It looks almost identical to ours, and we built this without ever seeing a picture of the inside! The basic concept is to use a boating bilge pump to circulate iced water through a heater core, then use 12V fans to blow air through that core, which cools the air and pulls out water through condensation.

Advantages: Very compact and portable, lightweight without the ice, no environmentally not-so-friendly chlorofluorocarbons, hydrogenated chlorofluorocarbons, or hydrofluorocarbons, very quiet, and operates off 12VDC, AKA a cigarette lighter. The only disadvantage is that it the ice will melt after 30-60 minutes of operation, depending on the size of your cooler. However, it was built for an EV, so we are only ever out for an hour or two maximum, and the ice lasts longer when it's not running. The third image on this step shows the operation. Have I convinced you to build one yet?

Comments

[awawawaw]

Woohoo! I just bought my ice chest to start mine and have the fan mounted so far. My first one will be cooling my 86 Accord for the 95+ days in Sac, CA. The second will be a gift for my father-in-law for his almost completely restored 1969 Nova. Target has a really nice cooler that has a "compartment" in the top for cell phones, keys, etc. This compartment works perfect for a 4.5" muffin fan. When mine is complete, it will still look like an off the shelf cooler. Go to target.com and search for "Igloo Ice Cube 14-qt. Cooler ". Hopefully mine will be completed in a week or so. (wish I had it today.... 101 forecast!!!)

[awawawaw]

Just went to check something on my ice chest and it looks like Target.com doesn't have it anymore. The one that comes up as the Igloo Ice Cube is 17" cubed. Mine is only about 12" cubed. It looks the same though........ I put all my parts together and ran a test. With 4 cups of ice and about a gallon of water, the air coming out was 58 degrees. As soon as I finish modifying the heater core (soldering on elbows) I'll post pictures and maybe an instructable.

[CameronSS]

Picture! Picture!

[awawawaw]

Still prototyping, but here is an idea. Ford Escort Heater Core: new at Kragens for $40, shown with the ends cut short and elbows soldered on Attwood T-500 Bilge Pump: $17 at Walmart ComAir Muffin Fan, 12V, 102CFM, Free from the garage Igloo Ice Cube 14qt ice chest: $15 at Target Heater hose: free (going to change to vinyl tubing for flexibility) Rocker switches: free from garage, one for pump, one for fan AC Adapter for Testing, 12V, 4.5Amp: from the workbench So I am into this for $72 so far, but I am buying most items new . Hoping to finish by the weekend.............

[rbfe4ch47]

hey there cameronss, love the idea. in fact had to go out and build one myself. i made a couple of modifications to it. i put a vented drain cap on the top and put the fans so they blow on the heater core. the warm air then is blown over the cold heater core thru the chest and out the vent. i also added a little on/off switch to it. i fly on helicopters and it gets mighty hot sometimes, this was the perfect little idea to cool off with. thanks for the idea.

[metaljoe0]

in chinook helicopters we have a system that cools water, then pumps it through little tubes in a vest that we wear to cool you down. it works well in an aviation application where you will be sitting not moving for a very long time with lots of ambient air blowing all around.

[CameronSS]

Don't let the FAA see it, they'd probably yell at you for it not being TSO'ed. ;-)

I'm glad to see that another person built one, and even more so because it's in the application that KoolerAire was trying to gyp $500 for.

_{My air conditioner is in a helicopter! Yay!}

[03CR250]

I was wondering about doing the same thing you are would it be better to blow into the heater core or is that just a theory cause id like to know i want to build a good one for my shop. also i considered using dry ice on those extra hot days to keep the water even cooler. we have a fridge in the shop so ice could keep coming and keep it cool all day. i might need 3 or 4 of these though its like 800 square feet. let me know what you think.

[rbfe4ch47]

it is actually better to blow into the heater core. the fans are more efficient for blowing. i made another one for a guy that worked better when i used a flexible pipe for a dryer. i added another fan to that so that two fans would blow on the heater fan and the added fan would suck that air thru the dryer vent. the dryer vent allows the person to be able to direct the air to whereever you would like. if interested, i could send you some pics of this one. the are a blast to make and if you have a dremel, that will make life easy. thanks for the comment.

[CameronSS]

You cannot cool your shop using ice that is frozen inside the shop. Ice is water that has had enough heat energy removed for it to solidify. If it is frozen in a freezer, all of the heat energy that is removed (and then some) is dispersed from the coils on the back of the freezer. Since all of the heat is being dispersed back into the shop air, you won't cool anything. Since your shop is stationary, you might as well just get a cheap window unit. It will blow cold air, but all the removed heat will be blown outside, and you won't have to replace ice and water.

[xvitox]

ummm dry ice= bad idea for anything like this...it wont work and if you seal up the area, as in to keep it cool inside, you fill the room with CO_2_ which brings about a very drowsy feeling. I know cuz that happened when I purchased Dry Ice one day and got stuck in traffic...and me and my girlfriend had the windows up. And it felt really good but we started getting sleepy.

[ironjudas]

Dry ice cant be put into water it will dissolve in seconds. Btw, do you need to keep supplying it with ice?

[pddonovan2011]

I have an S10! I would put the cooler in the toolbox, immediately behind the cab, and run the tubes into the cab with major insulation on both. Use a small high performance oil cooler in the cab and a cheap one in the cooler as exchanger. Use a small (One quart) plastic container as a surge tank, put a pin hole in the cap and leave two inches for sloshing. Fill with 50/50 Coolant and water, place exchanger on the bottom of the cooler and cover with dry ice! Cooler is outside the cab, cooling radiator is lower than the cooler (easier on the pump, a smaller one could be used and in the cab, making more room for dry ice!) Place the cooler in a box with three inches around it and pour in expanding foam to hyper insulate the cooler! I think this would make a really cold A/C unit!

This is a really great Instructable! It really got my creative juices flowing, thank you so much for that!

In the teardrop, if you are camping next to a stream, you can use two long hoses and a funnel to catch the water flow, divert it to the Teardrop where the pump can take over and pump it up into the teardrop. The teardrop is cooled and then the water is returned to the stream! Call it a "Gone Green A/C Cooler!" Hey, come to think of it, that would supply the Teardrop with a source of water that could quickly be purified using a ceramic filter for consumption!

[Redstormx1]

http://www.instructables.com/id/Home-Made-Freezer-Box-FridgeAir-con-/

[hagrawal3]

hey i have also made an a.c. com. heater and it works great!!!!!

[2be994510]

CameronSS: Nice work! I have read most of the comments and found them interesting. We are in the process of building the unit now with some modifications. If it works well then we will go to a larger system. Best wishes from Thailand

[deac02]

If creating ice is a problem and not green why not build a solar ice maker. Add in a solar charger for the battery and bang, boom it is almost self sufficient. Cool.

[twarner1]

The alternative to having this machine is having the existing AC fixed, which costs not only much more money, but is also more harmful to the ozone. A oil fueled Chlorofluorocarbon machine in essence!

[DIY Dave]

Sorry if I missed something, but how do you keep the water from splashing into the fans?

[CameronSS]

The heater core is between the fans and the water. Splashing isn't a concern unless you knock it over.

[DIY Dave]

Thanks for the quick reply

[showbizkid83]

Can dry ice be used as a cooling tool.

[guitaristjosh83]

i could probably find the answer to my question if i were to go through and read every single comment... but can you please tell me a quick and easy answer? should the fan(s) blow down through the heater core and into the cooler, forcing air out from under the cooler lid, or should the fans blow upward away from the cooler, sucking cooled air that passes through the heater core? i need to know which works best (not in theory, but in actual use and testing) before i build mine. thanks.

[Hunter Wolf]

Question: Would this cool a 10x10x8 (LxWxH) foot room?

[CameronSS]

Much larger than a car/truck cabin. Much better-insulated than a car/truck cabin. It would become cooler, that much is inevitable. How much and how long would depend on what exactly you built.

[asiddiqui attari]

What shall be the size of heater core and whether it should be a 1line heater core or 2 line heater core.
Is there any substitute for heater core?

[CameronSS]

As big as it needs to be to fit.
Doesn't matter.
Coil of copper tube? Anything like that.

[tazz1781]

While its a great project, its not all that green. For example, where does the ice come from? A machine that produces heat to make Ice and uses harmfull gases to do so. So, for the continued cost of the ice, whether buying it daily or having your ice box run more so you can provide your own ice, your really not saving any money or the enviroment.

[lloydrmc]

...and which "harmful gases" might those be, and in what way are they harmful?

[lloydrmc]

My "ice box" runs more? How much more would that be?

And agritzmacher has a point - how do you think electric cars are charged?

The raw materials and manufacture of Prius batteries requires 10,000 miles of transport, literally across the world: http://www.carkb.com/Uwe/Forum.aspx/car-driving/9345/A-Prius-Causes-More-Pollution-than-a-Hummer

Virtually all CFL bulbs - which we will be required to buy soon - are made in Chinese factories, fueled by "dirty" coal power plants. And they contain mercury, which, if the bulb breaks, requires approximately 6 types of tools and materials, and 14 steps (including cutting out a section of your carpet, if that's where it broke) - depending on who you ask.

[CameronSS]

Point 1: Do your research. Power from a coal power plant is cleaner than power from a gasoline engine.

Point 2: A CFL typically contains 4mg-5mg of mercury. The energy saved compared to an incandescent translates to something like 15mg-20mg less mercury vapor at a coal power plant.

Point 3: I made it to Level 2, I guess.

[lloydrmc]

Do YOUR research!
Point 1: Power plants in China (where virtually all CFLs come from) are NOT in any way shape manner or form: "cleaner than power from a gasoline engine". They have no scrubbers or any other type of pollution control whatsoever! In some Chinese cities, the smoke from power plants and other pollution literally makes it difficult to see for any distance, even at midday. http://news.nationalgeographic.com/news/2007/07/070709-china-pollution.html

Point 2: Try actually reading my comment. My comment was NOT about the impact of mercury on the environment in general but rather what a nightmare it is to have to clean up after a mishap with a CFL that we are going to soon be FORCED BY LAW to purchase, e.g.: http://www.maine.gov/dep/rwm/homeowner/cflreport/appendixe.pdf

Have you ever actually used a high-lumen CFL (such as a replacement for the soon-to-be-outlawed 100W Edison bulb)? It is recommended that they only be used in applications where they will be on for at least ten minutes, because it takes 5+ minutes for them to reach rated output

[CameronSS]

Okee dokes. Have fun.

[agritzmacher]

The same reasoning can be applied to electric vehicles plugged into the electric grid to charge... Just sayin'

[CameronSS]

The ice box runs whether we use the ice or not. We can turn it off, but that only shuts off water, not power to the freezing mechanism.

[tazz1781]

Yes, the ice box runs regardless, but it runs more to freeze water. How about using solar panels to run your portable cooler, or to charge the battery? Then you would have a somewhat "Green" portable AC.

[CameronSS]

Well, why do you think I'm tying to win? I don't need another bike...

[jpnagle59]

Cameron-- I live in Texas, Waco Texas, and so far this 'spring' we have hit 101 and 102 in my area. I have a 1993 Honda Civic, 200,000 miles on it, and the air is/has been gone now for a year and a half. This is one of the most brilliant ideas I have ever come across. Hat's off to you and your Father. I am late on this in terms of 2007, but I have a question if you could take a stab at it, I would be most grateful.
Do you think this design will cool a 4 door Civic to a comfortable level here in Texas when it is 100 outside? I suspect we would go harder on the ice, ie, it will melt quicker, but I am an older disabled person that has a harder time as I age with the heat. I sure would like to hear what you have to say to my questions.
I also wanted to say that I know the head of the physics department at UT Austin. I am going to ask him if there is a way to add something to the water to make the ice/cold last longer. Without using salt, and non-corrosive to the heat exchanger. If he gives me a good answer, I will let you know. one more thing- may I have you and your fathers approval to build your idea??? Tahnks so much, james

[CameronSS]

A Civic is pretty small, so it probably would. The ice wouldn't tend to melt any faster, it just wouldn't be as effective in a larger volume. Keep in mind, though, that a seven-pound sack of ice only lasts a couple hours, so it may not be cost-effective for all-day cooling unless you can find a place that has free ice. Here in Topeka, the Lindyspring water plant often dumps gallons of ice out on the lawn...a place like that would be good. Of course you can build it! That's the point of Instructables-to show what you built and how you built it, so that others can do it themselves.

[jpnagle59]

Thank you CameronSS...hats off to you and your father...