Is There Such Thing as a "Windowless" AC? Good Questions: Is There Such Thing as a "Windowless" AC? I live in a small windowless room in the middle of a railroadLast weekend's heatwave left me realizing that I basically live in an oven. I want to get a little portable air conditioner but while many are called "windowless" this is actually a lie as they require a window to stick the filter tube out of. What exactly is this tube for? Is there any way I can get around my no window dilemma and air condition this hot box room of mine? I'm dreading the summer! The windowless in those portables means that it doesn't mount into the window, but it does require the window for venting. We do not believe that there is ANY AC unit that doesn't require some venting as it must displace the hot air that it creates from making cold air. The best thing you can do is to create some kind of cross breeze - hopefully with the cooperation of whoever has access to the windows on either side of you.