Abstract: An air conditioning unit of the type adapted for installation externally of the space to be conditioned includes an outer housing separated into internal compartments by interior partition means and includes a belt-driven blower in one compartment for forcing air through heat exchanger means including a refrigerant evaporator, with the motor for driving the blowers being located in a compartment separate from that in which the blowers are located, the motor being cantilever mounted on a wall between the compartments with means provided to fasten the motor so that it may be shifted toward and away from the blowers to adjust belt tension but without uncovering an opening in the wall through which the blower motor shaft projects. Thus motor heat is prevented from mingling with the air which is blown across the refrigerant evaporator.