Air conditioning is an incredible invention, one we are all thankful for. AC, as we know it today, was first devised in 1902 by a young man named Willis Carrier. It is said that he stood on a train station platform in Pittsburgh, peering into the fog. Suddenly, he realized he could dry air by passing it through the water to create fog.
But even into the 1930s, air conditioning was used only in movie theaters and other luxurious places, but it was not until the 1950s, in the post-World War II economic boom, that residential air conditioning became popular. Suddenly, more than 1 million air conditioning units were sold in 1953 alone. By the 70s, window units were losing their popularity as the central air was developed. The units consisted of a condenser, coils, and a fan.