Heat is absorbed from the inside of a refrigerated area through the evaporator coil. It is then delivered to the condenser where it is dissipated in the air outside the refrigeration unit.
Look at figures 1 and 2 to see the route the refrigerant takes, and how it vaporizes or changes back into its liquid state as it is circulated through areas under different pressures.
The compressor is the heart of a refrigerator, freezer, air conditioner, ice machine, etc., all of which operate on the same principle. The compressor circulates refrigerant throughout the system by creating a pressure difference.
The compressor suction power from its suction port reduces pressure in the evaporator, causing the refrigerant to vaporize upon reaching there, absorbing the heat in the freezer compartment (essentials 1 and 3). It is then drawn into the compressor and compressed and forced into the condenser through the compressor discharge port. This action creates high pressures that speed up the refrigerant molecular motion causing the cold vapor to change to hot vapor. In the condenser coil, this added heat, and the heat absorbed in the evaporator, is radiated into the surrounding air causing the vapor refrigerant to cool down and return to its liquid state (essentials 2 and 4).
The liquid refrigerant is then circulated through the filter-drier and capillary tube on its route to the evaporator coil connected to the suction side of the compressor.
The suction power of the compressor creates a very-low-pressure environment in the evaporator, low enough to vaporize the refrigerant.
Once the refrigerant reaches the evaporator low-pressure environment, it is immediately vaporized, and heat from its surrounding area is absorbed, causing the unit to cool.
The cooling cycle continues until a preset temperature is sensed by the cold control (thermostat) causing it to disconnect the electrical circuit to the compressor. With the compressor shut off, the whole cooling operation stops and the temperature in the refrigerator rises.
When the temperature in the refrigerated area rises to a predetermined point, the contacts within the thermostat will expand and come in contact with one another (close), causing power to flow to the compressor. The unit resumes running, and the cooling cycle begins again.