I recognize that my home is tiny enough so that I don’t need an HVAC system. I choose to keep a few space heaters around for the winter and rely on window A/C units for the summer. I was quite surprised when I recently had maintenance done on my window air conditioner unit. I only need three window A/C units. I have one unit in my living room, one unit in my bedroom, and one unit for the guest bedroom. The window air conditioner unit in my bedroom in particular did not seem to be working very well. It just seemed to be too warm in there, no matter what I set the thermostat to. I had no idea what was wrong, so I called out an HVAC technician to check on it. When he arrived and examined the window A/C unit in my bedroom, what he had to say about its performance genuinely surprised me. For instance, I had not thought about the fact that the little bit of insulation around the edges of the AC unit was not sufficient in keeping out warm air from the outside of the window. Apparently, I needed to thoroughly weatherstrip around the A/C unit to keep cool air from escaping and warm air from coming inside. He also mentioned something that shocked me even more. I keep my PC tower right next to my window A/C in order to take advantage of the extra cooling that my PC gets from it. It turns out that the heat from the PC tower was sending misinformation to the thermostat on the window A/C that caused it to work harder than it needed to to cool the room! I would have never thought of such a thing!