My barns are cooled by large swamp coolers. At the beginning of spring the bearings needed oiled, the pads needed replaced, and I ordered a couple of extra water pumps to keep on hand, because we live 30 miles from the nearest store that MIGHT carry them. I also run a half gallon of vinegar through the pans about once a month to help keep the hard water from taking a toll on the equipment. It does a good job of keeping the barns(which have insulated walls) at a comfortable temperature while not having to deal with the ammonia build up many folks with air conditioners have to contend with. We also enjoy the fact they are cheaper to run, although they were probably more expensive to start off with. Yes, we have a few humid days a year they don't work quite as well- but this IS oklahoma- land of the summer drought. :) Notice the vent at the roof peak? That keeps the air moving through the barn and at the top- it keeps the hot air moving on through. So what about you? how do you keep your bunnies comfortable in the hot weather?