What Is a Freezer Compressor?

A freezer compressor is a mechanical device that is powered by electricity and found in most conventional refrigerator and freezer units. The freezer compressor is one of the main components that allow a freezer or refrigerator to operate. The job of the freezer compressor is to take cold gas that is emitted from the freezer area of the larger unit and place it under pressure until the gas raises in temperature, after which it can be recycled through the refrigeration system to keep the unit cold inside. The internal workings of a traditional freezer compressor use a capacitor-style motor to draw gas into a separate area, increasing its pressure as it moves. Over the lifetime of a standard refrigerator or freezer, the constant activation and deactivation of the compressor can lead to problems that require maintenance or even complete replacement.

Within the system that makes a refrigerator or freezer function, the freezer compressor sits between two sets of pipes or tubes known as the evaporation coils and the condenser coils. Depending on the design of the freezer, the compressor generally is located in the back of the unit near or on the floor. When the compressor is activated, an audible humming noise usually can be heard coming from the refrigerator, while there usually is silence when the compressor is not active. Cooling inside the freezer or refrigerator occurs only if the freezer compressor is running properly.

A refrigerator or freezer operates by passing a gas that is hot and under high pressure through a sequence of coils located on the back of the unit until it starts to cool. Once cooled, the gas condenses into a liquid and is passed through a pressure valve that reduces the amount of pressure it is under, immediately causing it to boil and return to a gaseous state and reducing its temperature dramatically. The cooled gas is then passed through another set of coils inside the freezer compartment that draws heat out of the compartment and into the gas, which continues to cool as it loses pressure. The low-pressure gas eventually is drawn out of the unit and re-compressed to start the process again.

In this system, the freezer compressor is responsible for taking the cold, low-pressure gas that comes out of the freezer compartment and pumping it into a separate area until the gas is compressed and once again under high pressure. The compression of the gas causes an increase in temperature. When done, the gas is allowed to escape from the compressor and eventually pass back through the pressure valve to start the refrigeration process all over again.

The freezer compressor is controlled by a thermostat inside the freezer unit. This causes the compressor to turn on and off constantly over the course of a day. In time, the compressor can run into problems because of this and can malfunction, requiring maintenance. The level of heat generated by compressing the gas also can cause the oil inside the device to heat and become a thick, dirty coating that can inhibit efficient operation.