Why Isn’t My Fridge Defrosting Properly? A Guide To Potential Causes And Fixes

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Are you worried that your fridge is not defrosting? Family members will open and close refrigerator doors multiple times as they store and retrieve food and drink. Every opening and closing of the doors allow air from the room to enter. Frost will form on the food items and cooling coils inside the freezer due to cold surfaces causing moisture in the air to condense.

Over time frost that is not removed will build up eventually forming solid ice. The defrost system prevents frost and ice buildup by periodically initiating the defrost cycle. There can be several reasons why your fridge isn’t defrosting properly. Here we will take you through a guide to potential causes and how to fix them.

Defrost Heater: A Crucial Component

The defrost heater is a crucial component in the defrosting process of a refrigerator. It is responsible for melting the frost and ice that accumulate on the evaporator coils, allowing proper airflow and preventing ice buildup that can affect the cooling efficiency of the fridge.

The defrost heater is typically a heating element that is placed near the evaporator coils. When the defrost cycle is initiated, usually controlled by a defrost timer or an electronic control board, the defrost heater is energized and heats up. This heat is transferred to the evaporator coils, melting the frost and ice.

There are different types of defrost heaters used in refrigerators, including:

  • Calrod heater: This type of heater consists of a resistive heating element encased in a metal sheath. It is commonly used in older refrigerator models.
  • Glass tube heater: Glass tube heaters are more commonly found in newer refrigerators. They are made of a glass tube containing a heating element that is similar to a conventional incandescent light bulb.
  • Defrosting coils: Some refrigerators use a set of copper or aluminum coils that serve as both the evaporator coils and the defrosting element. When the defrost cycle is activated, a small amount of hot refrigerant is diverted to these coils, melting the frost.

If the defrost heater malfunctions or fails to heat up properly, it can result in insufficient defrosting, leading to excessive frost buildup and impaired cooling performance. In such cases, the defrost heater may need to be tested and replaced if found to be defective.

Defrost Thermostat: Regulating The Defrost Cycle

The defrost thermostat plays a crucial role in regulating the defrost cycle of a refrigerator. It is responsible for monitoring the temperature of the evaporator coils and controlling the activation and termination of the defrost cycle.

The defrost thermostat is typically a bi-metallic switch or sensor located near the evaporator coils. It is designed to sense the temperature of the coils. When the temperature drops below a certain threshold, indicating the presence of frost or ice, the defrost thermostat closes its contacts and initiates the defrost cycle.

Once the defrost cycle is activated, the defrost heater turns on, generating heat to melt the frost and ice buildup on the evaporator coils. As the coils warm up and reach a specific temperature, the defrost thermostat senses this and opens its contacts, terminating the defrost cycle. This allows the refrigerator to return to the cooling mode.

If the defrost thermostat malfunctions, it can lead to issues with the defrost cycle. For example, if the thermostat remains closed or fails to sense the correct temperature, the defrost cycle may not initiate, resulting in excessive frost buildup and impaired cooling performance. Conversely, if the thermostat remains open or fails to terminate the defrost cycle, it can cause inadequate cooling.

If you suspect an issue with the defrost thermostat, here are some steps you can take:

  • Test the thermostat: Using a multimeter, you can test the continuity of the defrost thermostat to check if its contacts open and close correctly based on temperature changes. If the continuity is not as expected, the defrost thermostat may be faulty and require replacement.
  • Inspect for physical damage: Visually inspect the defrost thermostat for any signs of physical damage or wear. If the thermostat is visibly damaged, it may need to be replaced.
  • Consult a professional: If you are uncertain about performing the tests or if the defrost thermostat needs to be replaced, it is advisable to consult an experienced fridge repair technician from the Appliance Repair Center. They have the expertise to accurately diagnose and replace the faulty defrost thermostat.
  • Defrost Timer: Maintaining The Cycle
  • In refrigerators, the defrost timer is responsible for maintaining the defrost cycle, rather than the defrost thermostat.

The defrost timer is a component that controls the timing and duration of the defrost cycle in a refrigerator. It ensures that the defrost cycle occurs at regular intervals to prevent excessive frost buildup on the evaporator coils.

The defrost timer operates on a set time schedule, typically in the range of 6 to 12 hours. It has different settings for cooling and defrosting modes. During the cooling mode, the compressor and cooling components are active, maintaining the desired temperature inside the refrigerator. Once the set time period elapses, the defrost timer switches the refrigerator into the defrost mode.

In the defrost mode, the defrost timer interrupts the cooling operation and activates the defrost components, such as the defrost heater and, in some cases, the defrost thermostat. The defrost heater heats up, melting the frost and ice that has accumulated on the evaporator coils. The water resulting from the melting process typically drains away through a defrost drain.

After a set duration of defrosting time, the defrost timer switches back to the cooling mode, resuming normal refrigerator operations. The timing of the defrost cycle varies depending on the specific model and brand of the refrigerator.

If the defrost timer malfunctions, it can lead to issues with the defrost cycle. For example, a faulty defrost timer may not initiate the defrost cycle at the scheduled intervals, resulting in excessive frost buildup and poor cooling performance. In such cases, the defrost timer may need to be tested and replaced if found to be defective.

It’s important to note that not all refrigerators use a mechanical defrost timer. Some modern refrigerators employ electronic control boards that perform similar functions as the defrost timer. These control boards use sensors and algorithms to determine when to initiate the defrost cycle based on factors like usage patterns and frost accumulation.

Faulty Defrost Control Board

The defrost control board is responsible for monitoring various factors, such as temperature, time, and frost accumulation, to determine when to initiate the defrost cycle and control its duration. It receives input from sensors and other components in the refrigerator to make decisions regarding defrosting.

If the defrost control board is faulty, it can cause issues with the defrost cycle. For example, it may fail to initiate the defrost cycle when necessary, resulting in excessive frost buildup on the evaporator coils. Alternatively, it may activate the defrost cycle too frequently, leading to a shorter cooling cycle and potential temperature fluctuations.

If you suspect a problem with the defrost control board, here are some steps you can take:

  • Check for error codes: Some refrigerators with electronic controls display error codes when a component malfunctions. Refer to the refrigerator’s manual to see if it provides information on interpreting error codes related to the defrost system or control board.
  • Power cycle the refrigerator: Sometimes, a simple power cycle can resolve temporary glitches. Unplug the refrigerator from the power source for a few minutes, then plug it back in. This action can reset the control board and may resolve minor issues.
  • Inspect for visible damage: Visually inspect the control board for any signs of damage, such as burned components or corrosion. If you notice any visible damage, the control board may need to be replaced.

It’s worth noting that the exact process of troubleshooting and replacing the defrost control board can vary depending on the refrigerator model and brand. Therefore, it’s best to refer to the specific appliance care manual or seek professional assistance for guidance tailored to your refrigerator.

Conclusion

We know how challenging it can be to deal with a fridge that isn’t defrosting properly. This can lead to a variety of problems, from frozen food to potential fire hazards. If our guide hasn’t helped you resolve the issue, don’t hesitate to reach out to the professionals. At Appliance Repairs Centre, our skilled technicians are ready to bring your fridge back to perfect working order.