I've had my A/C going since about April. My apartment is great in the winter, but hell in the spring and summer because it retains heat like crazy. Plus gets a lot of direct sunlight all morning through midday. Add that to the heat generated by the amplifiers and TV/projector and I'd hit 85-90 in here (with an outside temp of 80) no problem and it's not that I'm even that hot, but I know the heat and humidity from not having it on would kill my stuff. General rule of thumb for me is that whatever my desk thermometer reads, the entertainment stand amplifier shelves will be, at minimum 10 degrees higher and that's with 7-200mm fans.