"mm" wrote
I already know I need a new furnace, and everyone says if my AC is 31
years old, I can buy a more efficient one. (Not that I disagree, but
when I only use it zero to 15 days a year, it's probably still cheaper
not to replace it. Until it broke, that is.)

I used to run our (window) AC about the same. As we get older and health is
not quite as good. I'm quick to flip the switch these days.