Troubleshooting Why Your Refrigerator is No Longer Defrosting

VIA Appliance
August 22, 2019
Refrigerator Repair

For most homeowners, they don’t have all of the same appliance woes as their parents did thanks to constantly evolving appliance technology. Most people will never know the struggle of having to scrape out a freezer full of frost thanks to modern defrost mechanisms installed in their refrigerators. However, if the defrost in your refrigerator is no longer functioning properly, frost could be a very real problem in your future until you fix what is broken.

Troubleshooting Non-Functional Defrost

When you have frost build up in your freezer section, there is only one cause – your defrost is not working as it should be. However, the defrost is made up of several parts, and if only one of which is not functioning properly, it can make the whole cycle non-functional. Until it is fixed, you can expect to have your freezer taken over by frost build-up. However, some parts of the defrost are more likely to be at fault than others, so here is where to start your investigation.

Defrost Thermostat

The defrost thermostat keeps track of the temperature of the evaporator coils in your freezer. While the defrost will turn on automatically in most cases, the thermostat helps aid in the process of when it needs to turn on and when it should turn off. However, if it has gone faulty, it will prevent the defrost heater from turning on, which completely stops the process. The thermostat doesn’t manifest special symptoms when it malfunctions, but you can test it for continuity with a multimeter to find faults. It is a small part, but even small malfunctions can have major effects.

Defrost Timer – Mechanical or Electronic

The timer sets the defrost cycle to run automatically at certain points throughout the day to prevent frost build-up on the evaporator coils. To test to see if the mechanical timer is the issue, you can manually turn on the defrost cycle through a dial-in your freezer. A malfunctioning timer will mean that even when done manually, the defrost cycle will not turn on, or alternatively, will not shut off within 30 minutes. If your freezer is warmer than normal, it can also mean a faulty defrost timer that is not shutting off the heater so the compressor can kick back on. However, in this case, you will notice that your food is not being properly frozen rather than frost build-up.

Many newer designs will use an electronic board in place of the mechanical timer and these can be a little trickier to diagnose depending on the model and brand of your refrigerator. Call our team today to schedule a technician to diagnose the more advanced designs.

Defrost Heater

If the thermostat and timer check out, then it could be the heater assembly itself that has gone faulty. As you would expect, the heater produces the heat that will melt away frost. If not functioning, then the frost will not melt away. You can test this part for continuity with a multimeter but is better to test the above options first. As the heater assembly is a major part of your refrigerator, it can also be a pretty involved repair.

Defrost Control Board

As you would expect, the control board is the brain of your entire defrost cycle. It controls every aspect of the process, but if it is faulty, the defrost will never turn on. Even if you attempt to turn it on manually, nothing will happen. This can help you narrow down the problem.  Homeowners should always leave this check for last, as it is the least likely part of your defrost to fail. However, if you have checked all of the above, then it may, in fact, be a case of a faulty control board that needs to be replaced. Not only is this the least likely part to fail, but it is also the most difficult to replace, and many appliance owners may feel more comfortable leaving it to a professional.

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