Quote Originally Posted by Bucky View Post
If it weren't for the design where they require an open window, running your air conditioners backwards would be a lot more efficient than using the oven.
Quote Originally Posted by factotum View Post
There are airconditioners that are installed directly into the window rather than being an internal unit with a hose stuck out of an open window. The only problem is that the thermostat is on the "cold" side, for obvious reasons given the normal use case of these machines, so you wouldn't have any way of regulating the internal house temperature if you were to run the aircon backwards. (Not to mention the very real risk of just freezing up the internals of the aircon unit due to it being *much* colder and damper than it was designed for).
There's also the fact that the controls will be on the outside (making the thing hard to operate), and they are not usually designed to be exposed to the elements (possibly destroying your ability to control the thing entirely).

You are probably better off running your central heat and stuffing towels into the ducts that open in the rooms you want left unheated.