First, the energy to the motor causes the positive displacement compressor, whose maximum capacity is a function of the speed and volume of the cylinder displacement, to draw cold, low pressure refrigerant vapor from the evaporator and compresses it.
     Second, the high pressure, high temperature discharge gas passes through the natural draft air cooled condenser. The air circulates over the condenser by convection, and when it comes into contact with the warm condenser, it absorbs heat and rises. The cooler air underneath rises to where it may also absorb condenser heat. The gas is then condensed to a liquid and the heat is rejected into the ambient air.
     Thirdly, the liquid refrigerant passes through a pressure reducing capillary tube to the evaporator, at a low pressure. The device permits the flow of refrigerant into the evaporator to be at the rate needed to remove the desired heat load.
     Lastly, the low pressure, low temperature liquid in the evaporator absorbs heat from its surroundings, and evaporates to a gas, which is withdrawn by the compressor.