Abstract: An apparatus and method for preventing unauthorized entry into a structure through an opening containing an air conditioner. The present invention relates specifically to an apparatus and method preventing a window-unit air conditioner from being easily pushed into the structure and therefore allowing an intruder to enter through the newly opened window vacated by the window-unit air conditioner. Using clamps and a security bar, the security device of the present invention secures the window-unit air conditioner from being pushed into the building. The device of the present invention is a complete unit, and may be installed without screws.