I f you already have an air compressor, I'd use it. Don't need air conditioning.
But overall, I prefer a CO2 tank.
The Sept. issue of JP magazine reviewed 10 products to fill your tires on the trail. The best and fastest solution was the PowerTank CO2 tank.
They say it's "blazingly fast". It puts out 45 cfm. The 2nd fastest they tested was Kilby Air Boss at only 6.94 cfm which uses a compressor mounted on your engine not unlike an air conditioner compressor.
Not all tanks are 6 times faster than a compressor. It depends on the regulator. I think speed is important. It can easily take over an hour to fill your tires back up.
Here's the thread where I originally posted this info:
http://www.jeep-cj.com/forums/f32/onboard-air-10695/