Lol, yes that's true, and I sometimes have to tell tenants to get their conditioners out. But no the the ACs are out. The really stealth heat leak is when people don't actually shut their windows all the way. They close it so that there's no opening at the bottom but very often the sashes are not meeting in the middle and air is blowing through. You have to be sure the two sashes are meeting properly and use the window locks which pull them together. Every fall I have to go around the house checking each and every window to make sure it's actually closed.