My car's air conditioner broke and it is incredibly expensive to repair, so I decided to improvise! This is a great way to cool down a hot car.
It works on a car's cigarette lighter, with two easy to find computer fans and a common cooler. It took me a couple hours to make, and that was including the failures that you don't have to suffer through, thanks to this guide.
Step 1: Get Cooler, "fix" It.
I went with a small from Target that was only $13. The cooler must be hard, and this one had a swinging lid.
The first thing I did was use a Dremel to remove the lid (keep this, you'll need it). Then I cut two square holes, one in each side of the cooler, for mounting the fans. I already had two different sized fans, so I made different sized holes.
Step 2: Install Fans
Now insert two standard computer cooling fans into the holes. Make sure that they are 12v DC fans, because these are the easiest format to work with.
Also note that one of the fans should be pulling air into the cooler, and the fan on the opposite side should be pushing air out.
After I stuck the fans in the holes I used a little hot glue and duct tape to hold them in place, along with some weather stripping for insulation and waterproofing.
Step 3: Metal Grate
Everybody knows cold air falls, so the ice should be positioned over the fans. I took a metal grate I had, cut it to size, and added legs to support it just above the fan holes. Then I piled about 4" of ice on top of it. I also added some ice packs below the fans for good measure.
You can't see the grate real well in this picture, but the ice is being held above the fans:
Step 4: Wire Fans
This should have been the third step, but oh well. Find the positive and negative wires on the front fan, and extend them back to the rear fan. Twist the wire ends of the positive wires for both of the fans together, and then run one longer wire from that intersection to a 12v DC car plug. What you should have is a Y-shaped string of wires, with the positives from both fans going into the plug. Get it?! Now do the dame with the negatives.
You will (hopefully) end up with two fans that both turn on when you stick the plug in a car cigarette lighter.
Step 5: Put Lid Back On.
To keep the ice from melting you need to put the lid back on. Since the cooler now has fans sticking out of the sides, I used the Dremel to cut fan-shaped holes in the sides of the lid. It slides on smoothly, although it does not latch, which brings us to step 6...
Step 6: Secure the Lid!
Use a bungee cord to secure the lid! Remember, there is no latch now, so if you lift the cooler by the handle on accident, this happens:
Step 7: Done!
Done. It should look something like this. Oh yeah, it should also blow cold air out. If it doesn't look like this, or work at all, you probably did something wrong.