Abstract: A room air conditioning control system incorporates a motion detector strategically placed in the room to detect the presence of activity in the room and enable a room air conditioning unit to operate and thus adjust the room temperature to a pre-selected level. The motion detector, upon detection of motion within the room, switches a transmitter to transmit an RF signal to a receiver connected in the power line of the room air conditioning unit. The receiver connects power to the unit and maintains such power for a predetermined time after motion within the room is no longer detected. The motion detector and transmitter operate on battery power, and the control system operates without hard wiring to permit the system to be added to an existing room air conditioning system.