"Redneck AC" works during power outages where you have a generator capable of running your refrigerator/freezer but not your HVAC. Put some one or two liter plastic bottles filled halfway with water into the freezer - if you lay them on their sides the ice won't burst them. Once frozen put the bottles next to your snake enclosures or racks, with a small fan (you can get battery-powered ones) blowing air across the cold bottle toward your snakes. That will help cool the air in the small area around your snakes.
Covering windows and skylights also helps, but do it from the outside so the sunlight can't penetrate the glass.