Abstract: An air conditioner comprises upper and lower sections. Each section includes a heat exchanger, a fan, and a wall which is slidably between opposite sides of the air conditioner. The heat exchangers are pivotable relative to their respective fans. By sliding the wall and pivoting the heat exchanger of either section, that section can be placed in communication with either the inside ambient air of the ambient outside air for performing a heating or cooling function. The air conditioner can thus be reversed between heating and cooling functions without reversing the direction of refrigerant cooling.