Air conditioners and air coolers are both perfectly viable tools for keeping the room temperature down. The best choice really depends on the climate where the evaporate cooler will be located and also the budget of the owner.
Air coolers use water to cool the room. A side effect of this is that the humidity of the room is increased by an air cooler. Air conditioners, on the other hand, remove humidity by drying ambient air.
Air conditioners use coolants like Freon in order to cool the air. Environmentalists claim that coolants are harmful to the environment, so air coolers are more environmentally friendly by not using coolants.
Air coolers bring fresh air into the room and work best in open areas, while air conditioners circulate the air and work better in enclosed areas.
Air conditioners make up 5% of energy bills. Air coolers use water, which has an automatic cooling effect, reducing electricity bills by as much as 75%.
Air coolers need a lot of water in order to function, while air conditioners need a lot of ventilation in order to function.