Who invented the air conditioner?

The American engineer Willis Carrier invented the modern air conditioner. Carrier devised the first modern system of air conditioning in an attempt to resolve various quality issues at the Sackett-Wilhelms Lithographing and Publishing Company in Brooklyn. The system was put into operation in July 1902.

Many different systems for artificially cooling the air had been used for centuries, but Carrier's was the first to include a means of controlling humidity. Air was pumped through coils filled with cold water to both cool the air and reduce the humidity level. Carrier's invention was subsequently installed in many factories and office buildings to improve productivity and make working conditions more comfortable.