To explain, the evaporator inside your unit is the key player in removing the heat from the inside of your refrigerator, the evaporator side of your tubing section is often referred to by techs as the “Low Side” because it is inside this coil that the freon evaporates and absorbs heat while doing so, it is called the low side because the pressure inside it is low. However, a by-product of this process is condensation in the areas surrounding the evaporator coil, this condensation has a tendency to collect on the coils and form ice. This ice must have a mechanism for removal or it will in time cause a refrigerator to not function properly.
One of the key processes going on in your refrigerator is cool air flowing from your freezer to your refrigerator and it must move across the evaporator coils to function correctly. The problem is that if the coils are not defrosted, the ice will continue to accumulate on them and will eventually fill up the passages where air needs to flow through. The defrost system has several working parts which will need to be checked if your freezer is cold but the refrigerator isn’t.
There is a defrost timer which controls when the refrigerator shuts down the compressor and activates the defrost system, this usually happens for about twenty minutes every six or seven hours. Often the tiny motor in the timer which propels it will burn out, this usually happens when the refrigerator is in the cooling mode and leaves it stuck there which causes the ice to build up and for cooling problems to occur. Occasionally the defrost timer will get stuck in the defrost mode, however when this happens, your refrigerator will not cool at all.
After the defrost timer the next biggest culprit is the defrost heater, this is usually a single tiny strip heater at the bottom of your evaporator, although some models use two of them. In most of the cases I run into, this heater has shorted out and is no longer working, which has caused the ice to build up to the extent that air can no longer flow to the refrigerator side. While these are not too terribly expensive, they are not cheap. Difficulty of installation depends upon where they are located in the unit, however most of the time the biggest problem is de-frosting the huge block of ice your evaporator has created around itself so you can get in to actually replace the heater.
The third part of the defrost equation is the defrost thermostat. This is a switch normally setting at the top of your evaporator that senses heat and opens or closes an electric circuit based on temperature. When your evaporator is cold, the coolness causes the switch to close and allow electricity to flow through the defrost heater. However after the heater has been on awhile and melted the ice, when the temperature gets above a certain point the thermostat will open and cut off the flow of electricity and shut down the defrost heater.
The defrost system is usually the problem in roughly 80% of the calls I make for refrigerator repair, however there are a few other factors that can contribute to the problem. Some of them are covered in Part One of this series. The balance will be covered in Parts Three and Four.
In parting, if your problem is that your freezer is cooling but not your main refrigerator, try not to be too disheartened, at least you know the compressor is still working and creating coolness. Troubleshooting the defrost system and repairing it is something a good appliance tech can do in a few hours.
Brett Singleton is a free lance writer from Charleston SC. He is also a responsive web developer as well as a Charleston SEO specialist. He also works as a consultant on web design, SEO and marketing for Appliance Repair-Charleston, a company providing refrigerator repair services in Charleston SC.
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