Knowing how refrigerators work can be very useful when
working on refrigerators. On this page I will explain how they work so that you
can use this page in conjunction with my refrigerator repair guide to help you
fix your broken refrigerator.
In order for a refrigerator to work, refrigeration must take place. Refrigeration takes place in the sealed system. The sealed system consists of the compressor, condenser, metering device evaporator and suction tube. First a refrigerant such as R-134 or R-12 enters into the compressor in gas form and the compressor raises the pressure and the temperature of the gas. Then the gas enters the condenser (normally located under or behind the refrigerator) still in gas form and exits as a liquid. Next, the high pressure/high temperature liquid refrigerant enters a metering device or capillary tube on most refrigerators and exits as a low pressure/ low temperature liquid. Next, the low pressure/low temperature liquid refrigerant enters the evaporator (located inside the freezer) and exits as a low pressure/low temperature gas. Then finally enters the suction tube and exits into the compressor and the process starts all over. Refrigerators never run out of gas so this process can go on forever unless the gas leaks out.
Airflow is important in the operation of
refrigerators. The evaporator is located inside the freezer and provides cold
air for the fresh food section and the freezer. A fan located above the
evaporator blows air into the freezer and the fresh food section. The air enters
the fresh food section through an air duck. A damper controls the rate of
airflow into the fresh food section. Some dampers are manually turned by hand
and some dampers are controlled by an electric motor. There is also a fan under
the refrigerator to provide airflow through the condenser and over the
compressor. This helps with the condensing process and helps cool the compressor
so that it doesn’t overheat. If airflow is stopped or blocked inside or outside
the refrigerator, the refrigerator stops working properly.
During a defrost cycle, the
refrigeration is cut off and a defrost heater comes on to melt the ice off the
evaporator. Once the temperature reaches 47-50 degrees Fahrenheit, the defrost
thermostat terminates the defrost cycle. If you didn’t have a defrost cycle the
ice would eventually build up to the point that it blocks airflow. Refrigerators
go through a defrost cycle anywhere from once every six hours to once every 48
hours depending on the defrost control. There are two types of defrost controls,
adaptive defrost controls and mechanical defrost timers.
That’s the basics on how refrigerators work now a little on how they are
Refrigerators uses more electricity during defrost than any other cycle, so to make refrigerators more efficient manufactures started using adaptive defrost controls. An adaptive defrost control adapts the defrost cycle to your families needs. The more times the doors of your refrigerator are opened, the more often it needs a defrost cycle. On GE refrigerators with adaptive defrost, it goes through a defrost cycle once every 48 hours if the doors are not opened during that time. But the longer the door stays open between defrost cycles, the more often it goes into a defrost cycle.
Mechanical Defrost Timers
Unlike adaptive defrost controls, the time between defrost cycles is the same on refrigerators with a mechanical defrost timer. The time between defrost cycles will vary with each models. Some defrost every six hours for 30 minutes and some defrost every 12 hours for 35 minutes.
Refrigerators have two controls, one for the freezer and one for fresh food. The fresh food control is a thermostat called a cold control that cuts off the refrigerator when the fresh food section reaches desired temperature which is somewhere between 33 and 42 degrees Fahrenheit, by that time the freezer will be cold enough. On older refrigerators and some new refrigerators, the freezer control controls a damper that slows down or speeds up the rate that the air enters the fresh food section. So if you turn the freezer up, all you do is block airflow going to the fresh food section so that the refrigerator runs longer and the freezer gets colder. Normally it is best if this control is set midway and left there. On newer refrigerators with an electric damper control, the damper automatically opens and closes the damper, as needed depending on the temperature in the fresh food and freezer sections.
I hope this page helped you better understand how refrigerators work. If you have any questions about how refrigerators work you can visit my page on frequently asked questions about refrigerators.