Before I get started, I have to give props to Geoff Milburn, at http://www.gmilburn.ca/ac/ whose plan it was I copied. I'm not smart enough to think up something like this on my own. That being said, one of the places I work has no AC, but I'm allowed to have fans, so this seemed like a good project for me. It's not perfect yet, but it does cool the air better than just a fan.
Step 1: Attach copper tubing to the fan
I took the grate off of my fan, so I could put the heat exchanger on the inside, hopefully making it look better. I'm using copper tubing as the heat exchanger, although you could use something else, as copper is not cheap, and not easy to work with. As you can see in the second photo, it's very easy to kink the tubing, in which case, you stop the flow of water. I grabbed a hole saw to use as a die to wrap the tubing around, and the teeth held nicely against the grate of the fan. As I was going along, I used zip ties to hold the tubing to the grate. Of course, because this will be inside the fan, make sure to clip off the loose ends. Also, make sure that you have both ends of the copper tubing sticking out of the fan, so you can hook up the tubes to the pump.
Step 2: Attaching the tubing to the pump
Now, the cheapie pump I bought would only fit 1/2" ID tubing, and they didn't have anything that would downsize it to 1/4" for me, so I just rigged it up. As you can see in the first and second photos, 1/4" tubing fits quite nicely around the copper tubing. In the third photo, you can see how I just inserted the 1/4" into 3/8", into 1/2" tubing, which would then fit onto the pump. This of course leaked, which necessitated the use of hose clamps, photo 4. I feel that this greatly reduces the effeciency of my pump, but now I have a reason to buy a bigger, stronger, more manly pump! Either that, or buy bigger copper tubing, which is not as exciting.
Step 3: Submerging the pump and testing it out
I bought a foam cooler to hold my coolant(ice water), as I have easy (free) access to both water and ice. Once I had it all hooked up, with one tube going from the pump into the heat exchanger, and another from the heat exchanger back to the cooler, I submerged the pump and plugged it in. At this point you'll be able to tell whether or not you have leaks real quick. If you do, just shut it off and tighten things up. If you've got a hole in your copper tubing from over-zealous bending, you might have a tricky problem to solve. I didn't have that problem, so I couldn't begin to tell you how to solve it. (I am partial to JB Weld for all things broken though) I've noticed that towards the end of the copper tubing, I'm not getting any condensation, which means by the end, the water has lost it's cooling effect. When I get a bigger pump, the water will flow much faster, and hopefully won't warm up as much. Well, that's about it, any suggestions would be welcome!