Air conditioning is not directly harmful. It has always been known that families living in air conditioned houses make more babies than families without it.
When you move to a hot climate your body has to learn three tricks: sweat more, start sweating sooner, and grow 50% more blood volume. Newcomers are advised to avoid working outside, stay in the shade, and drink lots of water. The process takes three weeks. Air conditioning interrupts that process and makes the person quite uncomfortable when he has to go outside again. It is possible to die as a result.