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Symptoms Of a Bad Defrost Thermostat

fridge thermostat

A malfunctioning defrost thermostat can lead to several problems with your refrigerator, from inconsistent temperatures to excessive frost buildup.

Here are a few of the most common symptoms to look out for that indicate needing to replace it.


Signs Your Defrost Thermostat Is Broken

So, what are the symptoms of a bad defrost thermostat? Here are some of the most common signs to look out for.

Food Spoils Earlier Than Expected

If your food seems to spoil faster than it should, your refrigerator’s defrost thermostat may be malfunctioning. This component regulates the temperature in the fridge, so your food is more likely to spoil when it’s not working correctly. You’ll need to monitor the shelf life of any food you store in your fridge and replace the thermostat as soon as possible.

Frozen Evaporator Coils

The evaporator coils in your refrigerator can become frozen if the defrost thermostat malfunctions. This usually occurs when air is not circulating and the evaporator coils are not functioning correctly.

If you see frost or ice buildup on the walls of your fridge, it’s likely a sign that your defrost thermostat needs a replacement. Due to the frozen coils, you may notice that your fridge isn’t running as efficiently.

Excessive Frost Buildup Inside Fridge

Excessive frost buildup inside your fridge is another sign of a faulty defrost thermostat. The thermostat instructs the defrost heater to switch on once your refrigerator becomes too cold.

If you notice a buildup of frost inside your fridge, you should check the defrost thermostat is still working by conducting a continuity test.

Frosted up freezer

Temperature Fluctuations

If the internal temperature of your refrigerator keeps fluctuating, this is likely a sign that the defrost thermostat is malfunctioning. This can cause food to spoil quickly and increase energy bills.

Make sure you replace the thermostat if you experience any temperature issues with your fridge.

The best way to tell if the thermostat is the culprit is to check it with a multimeter. A multimeter measures the electrical current in your fridge and will tell you if the thermostat is not working correctly.


When a refrigerator’s defrost thermostat malfunctions, it can cause various problems that make it challenging to keep food fresh. If you experience any of the symptoms mentioned above, check the defrost thermostat by conducting a continuity test.

Fortunately, replacing a thermostat is easy and not too expensive. Just make sure to get the correct one for your particular refrigerator model.

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