I am of the opinion that air conditioning is not necessarily a good thing. It makes summer heat and humidity worse, because we spend our days in air conditioned environments and never get used to the weather outside.
When you have to wear a sweater indoors on a day that tops 90F, there's a problem with that.
My goal this year was to try my best not to use my air conditioner at all. I lasted until now... 74% humidity inside is just asking for mold and mildew problems. So tonight, I turned on the air, and it still worked. (If it hadn't, then oh well; I'm not replacing it.) But it worked, so I'll leave it on until I go to bed, then turn it off again.
Perhaps I won't have to turn it on again. But this time, at least, it was definitely not the heat. It was the humidity.