The Compressor
When the suction vapor is drawn from the suction line into the compressor, the cold refrigerant vapor absorbs heat from the compressor motor windings. If there is the proper amount of vapor present, the compressor will be cooled properly. If there is a lack of refrigerant vapor (such as an undercharged system), the compressor will run very hot.
After cooling the motor, the vapor is compressed to a high pressure/temperature gas and discharged into the hot gas line leading to the condenser coil. These hot gas temperatures average about 126F.The Condenser Coil
At the condenser coil, the heat from the evaporator and compressor is removed from the hot refrigerant (126F) to the cooler outdoor air. When the hot gas enters the condenser coil, it is highly superheated and at a high pressure. The purpose of the compression of this gas to higher pressures is to raise the saturation temperature above the temperature of the outdoor air. At the condenser coil, the heat picked up from the indoor evaporator coil and the heat from the compressor will be removed by the refrigerant by transferring the heat to the (relatively) cooler outdoor air. In this example we have a R-22 refrigerant at 282.7 PSIG which corresponds to 126 degrees. If R-410A is used, you will see that the saturation of 126F corresponds to 450 PSIG.
The hot gas leaving the compressor is highly superheated so its actual temperature is going to be above the 126F saturation temperature. Remember, the hot gas contains heat from the evaporator coil, compressor, motor windings, and the heat created by compression. As the hot gas enters the coil, it immediately begins to give up heat to the cooler outdoor air. The high pressure/temperature gas will continue to give up heat until it reaches its saturation temperature. In this example 126F, still much hotter than the outdoor air.At saturation temperature, any removal of heat will cause a change of state. In the example the hot refrigerant begins to condense into a liquid or change state, releasing massive amounts heat. The heat released while changing state is called latent heat. This heat is carried away from the outdoor condensing coil by the condenser fan.
by Ron Walker