Portable 12V Air Conditioner
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 [عزيزي الزائر يتوجب عليك التسجيل لمشاهدة الرابط للتسجيل اضغط هنا] 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 [عزيزي الزائر يتوجب عليك التسجيل لمشاهدة الرابط للتسجيل اضغط هنا] 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. 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.
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?
Ice Chest free, had it on hand If at all possible, get one with a hinged lid. Free from a storage shed or a dumpster. Or, the Igloo Ice Cube 14 looks like it would work,well, as do the Cool 16 and the MaxCold 24. We used an old 12 quart cooler, and it fit a 7 pound bag of ice.
Heater Core free, salvaged from a ’77 VW Rabbit we’re parting out You can find these on Also, I haven’t tried it, but Ufixitautoparts sells heater cores for under 5 bucks apiece.
Box Fans and Blade Guards free, from stock in basement They’re sold out of $5 [عزيزي الزائر يتوجب عليك التسجيل لمشاهدة الرابط للتسجيل اضغط هنا] boots sale uk 120mm 12VDC fans at All Electronics, but too. Under $10 on eBay.
Bilge Pump $10.44 for a 500GPH unit at Wal Mart The Attwood V500 was at our Wal Mart for $10.44 you can get a similar pump for under $10 on eBay.
Hose free, had it in stock Ours came from an auto parts store, but it can be found at hardware and auto parts stores for a dollar or so for a few feet.
12V plug free, chopped off a car accessory Cut one off an old phone charger or other device, or , or $3.75 at All Electronics.
Caulking free, from the stock in the shop Can be found near the bilge pump, or from a hardware store. A couple bucks.
Piano hinge (depending on cooler) free, in stock Only necessary if your cooler isn’t hinged. A couple bucks at the hardware store.
Inner tube piece (optional) free, blown tube You may or may not need this see step 7. If you do, use a blown one, or another piece of rubber, or come up with a substitute. You did save the last blown tube for future projects, didn’t you? A couple bucks, tops.
Assorted wire, wire nuts, and screws free, in stock Depends on what you have in stock and where you get it. It’s all at the hardware store, too.
Ice free, freezer’s ice maker If you need me to tell you where to get ice, you shouldn’t be doing this project.
An ice chest/cooler has a double lid with a cavity. This is convenient because we can cut separate holes for the fan and heater core.
On the underside of the lid, mark the outline of the heater core, then go in about a quarter inch and cut out a rectangular hole through ONLY the first layer. This will allow airflow through the core, but still make it easy to attach.
Next, you will need to mark the inside of the fans and cut out two circular holes. We originally planned to use a hole saw to cut the holes, but found that we didn’t have a bit that big, so we chucked a saw blade into the Dremel Rotary tool and zipped it out, of course wearing safety glasses (hint hint).
Tada! You now have a rectangle on the inside and two circles on the outside. Now that you cut out these lovely holes, lets fill them in.
The next step is to attach the fans. This is fairly straightforward simply drill a small pilot hole at each corner of each fan, and put a small screw through the bottom hole into the plastic lid. A bead all the way around seals the lid and provides plenty of bonding force to hold the heater core in place. Make sure to get the core centered, straight, and with the nozzles pointing in. If your lid is hinged, you will want to do a test fit before attaching the core to ensure that the nozzles clear the edges. If your lid is not hinged, it may be easier to attach it first. We ended up cutting the output off to make it fit better.
The ArcticAir unit just leaves their bilge pump just dangling from the hose, but we wanted it to be more secure. The pump has a twist off base, so we twisted it off and Gorilla Glued it to the bottom of the cooler. Make sure that it is angled so that you can easily run a hose from the pump output to the heater core input. We attached the base directly to the bottom of the cooler, which works fine, but we probably should have put some spacers in to increase water flow underneath. Also, the picture just shows where it goes. We haven’t attached that hose yet, so ignore it.
If you used a cooler with a hinged lid, skip this step. Otherwise, read on.
By hinging the lid, it makes it easier to open for loading ice and letting air flow in during operation. It also prevents the lid from sliding off and dribbling water out of the heater core while driving. You can use whatever you want for a hinge a rubber strip glued on, a couple of cabinet hinges, whatever. We used a piano type hinge that we found in our stockpile of random stuff. It goes all the way across the back, and allows the lid to [عزيزي الزائر يتوجب عليك التسجيل لمشاهدة الرابط للتسجيل اضغط هنا] flip all the way back, but still close completely.
This is fairly straightforward. Connect a hose from the output of the bilge pump to the input of the heater core. In most cases, it doesn’t matter which nozzle is used as the input. We just let the output dribble back in, but if the noise bothers you, you could attach a hose to the output. This would also be used as a drain hose.
We also attached a piece of bicycle inner tube rubber to catch water that drips from the output and that condensates on the core. It was cut to fit around the back edge and a couple inches up he sides, and secured with a mega rubber band we found. This may be unnecessary if [عزيزي الزائر يتوجب عليك التسجيل لمشاهدة الرابط للتسجيل اضغط هنا] you attach a hose to the output, or if your heater core is configured differently.
This would also be a good time to attach wire fan guards to the fans. Just put some screws through the guards into the top holes.
It would be difficult to make the make the wiring for a project easier than this. There should be a red and a black wire coming from each fan, the bilge pump, and the 12V plug. Use wire nuts to attach them all together, and make sure the pump and fans are going the right directions. The fans should be blowing out, and the pump should be pumping through the hose. After everything is moving correctly, you can solder the wires together, or put a switch in the power cord. We also used small zip ties to hold the wires together and to the fan.
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