What to Look For
The most simple camping air conditioning units are battery-powered fans or evaporative coolers. When opting for a fan, look for one designed to mount to a window so it can draw in fresh air from the outside while cooling the tent. More complex AC units require 12-volt power supplies and use ice chests to develop cold air to blow into your tent. Check to see whether the unit requires a power supply and determine if you'll be able to power it up in the woods. Also, consider other necessary supplies like water and ice required for use with tent air conditioners.
Verify that you need a tent air conditioner before spending money on one. While some avoid "roughing it" at all costs, many wilderness areas cool down significantly at night and may be comfortable in a well-ventilated tent without an air conditioner. Even scorching deserts get very cool at night. Remember, air conditioner units often require power sources and other equipment and take up extra room in what will likely be an already stuffed vehicle. Check weather reports and talk to other campers and forest rangers about typical nighttime temperatures before committing to a camping AC unit. You can also drop from a heavy sleeping bag to a camping sheet to cool down at night.
Where to Buy
You can find tent fans and air conditioners at outdoor sporting good stores like REI and Backcountry.com, as well as at large general retail outlets like Amazon. Two well-known camping companies that sell fans directly to consumers are Eureka! and Coleman.
You can find simple fans and evaporative coolers for between $15 and $60. More complex box units like the O2-Cool Portable Battery Powered Cool Box or the KoolerAire 12 V Portable Air Conditioner cost between $100 and $200.