If Willis Haviland Carrier is not a candidate for sainthood, he ought to be. Thanks to him, I can inhabit my beloved home state. As a child we had no AC, and I can tell your from that experience that without his invention to filter, cool and dehumidify the air in our homes, life Texas for asthmatics and allergy sufferers is extremely difficult during the summer months.
We didn't have AC when I was growing up either. With the exception of a few movie theaters and restaurants, I don't remember AC in widespread use until the late 1960s, early 70s. Most new automobiles didn't feature it until the 70s and even then it was an option.