<P> Designed to improve manufacturing process control in a printing plant , Carrier 's invention controlled not only temperature but also humidity . Carrier used his knowledge of the heating of objects with steam and reversed the process . Instead of sending air through hot coils , he sent it through cold coils ( filled with cold water ) . The air was cooled , and thereby the amount of moisture in the air could be controlled , which in turn made the humidity in the room controllable . The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment . Later , Carrier 's technology was applied to increase productivity in the workplace , and The Carrier Air Conditioning Company of America was formed to meet rising demand . Over time , air conditioning came to be used to improve comfort in homes and automobiles as well . Residential sales expanded dramatically in the 1950s . </P>
<P> Designed to improve manufacturing process control in a printing plant , Carrier 's invention controlled not only temperature but also humidity . Carrier used his knowledge of the heating of objects with steam and reversed the process . Instead of sending air through hot coils , he sent it through cold coils ( filled with cold water ) . The air was cooled , and thereby the amount of moisture in the air could be controlled , which in turn made the humidity in the room controllable . The controlled temperature and humidity helped maintain consistent paper dimensions and ink alignment . Later , Carrier 's technology was applied to increase productivity in the workplace , and The Carrier Air Conditioning Company of America was formed to meet rising demand . Over time , air conditioning came to be used to improve comfort in homes and automobiles as well . Residential sales expanded dramatically in the 1950s . </P>
when did a / c first appear in homes
when did a / c first appear in homes
1950s
1950s