I live in Florida, and even with my a/c cranking sometimes my back will still get hot due to the fabric seats. So I just finished adding a/c piping and large computer cooling fans into my drivers seat on my 92 camry. Here's a step by step of what I did for anyone interested.
First I took a 4 foot piece of flex piping that I got from the hardware store and fitted it to one of the rear feet vents under the drivers seat using aluminum ducting tape. In order to get the piping to fit into the narrow vent tube I had to use a hack saw to remove a pinched piece in the middle of it and then I squeezed the piping in. As you can see I also taped off the other vent to force as much air as possible into the piping.
Then I also taped off the vents under the passenger side seat, I'm not sure how much effect this have, but I figured the less places for the air to escape from, the more effective the piping will be, and the people in the back seat can just deal with it
Next I removed the seat-back. No tools are required, the top has 2 button snaps, and then you squeeze in the sides and lift. Once I got the back off, I used a sharpee to mark where I wanted to install the fans and run the piping as you can see.
I then traced around the fans where I wanted them so I would know where to cut out the foam.
Once it was marked off I used a razor-knife to cut out the foam. BE CAREFUL not to press too hard and go through the fabric of your seat. I didn't cut all the way through for this reason, and tore the deeper parts by hand.
You can see in that picture that the fabric will be the only thing that will be between you and the fan now.
Then I took the first fan and popped it into the hole. I slid it in from the top to get around the metal support for the seat. **Make sure you have the fan installed so that it will blow in the right direction!
Then do the same thing with the second fan. This picture came out horrible btw.
You can see I cut a little foam away where the piping will sit as well. Then I trimmed the excess piping to have it sit just under the fans. **Make sure when you cut the pipe to size you think about having slack to slide seat back and forth. I slid the seat all the way back, and then did the trimming.
Then it was on to the wiring. I crimped both positive wires together and both ground wires together so I would only have to run one set of wires. I ran the positive wire up to the dashboard by tucking it under the center console. I ran the ground wire to a screw on the frame of the seat as shown. Same thing with the wiring as the pipe, make sure you have slack so the seat can move.
After the wiring was run from the seat, I put the seat back cover back on. You're done back there. It was a bit tricky with one person, but you have to hold the piping up in place where you want it, then slide and clip the seat back into position. The piping gets squeezed by the back enough that it doesn't need any more anchoring or support.
Now all I had to do was wire up a toggle switch for the fans. I took power from the fuse panel behind the change compartment. There is an unused fuse in there for seat heaters which I didn't have so I put the wire in under the fuse. You can take power from anywhere. I chose this spot because it is only a hot wire when the key is in the on position so I can't leave the fans on by accident. Run a wire from there into the toggle switch, and on the other connector of the switch, screw in the positive wire you ran from the fans.
Then I drilled a hole in the trim piece around the radio where I chose to mount my switch, installed it, and put it all back together.
And that's it! Air conditioned driver's seat. It can double as a heater when it gets cold as well which is a perk in places other than Florida haha. This came out better than I expected. With the a/c positions set to the dash and feet position with the fan speed half way, and the seat fans on, I can feel the cold air with my hand from about 2 inches away. With the fan full blast it's stronger than that. I drove around for about 15 minutes after I finished this and I could feel the cool air hitting my back through my shirt. I got the fans from some old computers in my attic and the piping only cost me about 6 dollars, so its a great mod for the money. This is a feature BMW uses and now I have it on my camry. You could do the same thing for the passenger seat as well if you wanted, and even wire in a separate toggle switch. The entire project from start to finish including the prep and planning took me about 2 hours.