In my opinion. If you are going to do any kind of "AC" in a garage. Make it a swamp cooler. Swamp coolers work better in areas of high humidity, where as AC units are worthless. In a garage, if there isn't any insulation your humidity levels are going to a bit higher than they would be in your home. Hit up KSL and find someone who is selling a used swamp cooler. Replace the filters and possibly the pump and you'll be real happy. Just my 2 cents though.