When did they invent the airconditon?

Answer 1

Systems that cool the air by blowing it over or through damp cloths have been around for over a millennium. Those systems take advantage of the fact that heat is what fuels the evaporation process. As liquids evaporate they absorb heat from their surroundings. Those systems are not very effective in very humid climates, but they make a considerable difference in the desert. When used in conjunction with standard air conditioning they greatly reduce the cost of air conditioning in places like Phoenix or Las Vegas.

According to Wikipedia the electrical air conditioner was invented by Willis Carrier in New York State, U.S.A. in 1902. However, air conditioners like Carrier's were only practical for industrial use since they used several toxic chemicals in the cooling process which would have been far too dangerous to have in a home. Wikipedia goes on to say that the first non-flammable, non-toxic refrigerant chemical, dichlorodiflouromethane (a.k.a. freon) was developed in 1928 at Frigidaire, the refrigeration division of General Motors Corp. The first time a home was equipped with central air conditioning was in 1933. The first portable air conditioner designed to be mounted in a window was invented by Robert Sherman of Massachusetts, U.S.A. in 1945.

Immediately after World War II, refrigerators, which use the same cooling process as air conditioners, were rapidly replacing ice boxes in kitchens everywhere. Come to think of it, a refrigerator is merely a very small air conditioned room with the thermostat set very low. ;)