Bosch Refrigerator Is Not Defrosting – Troubleshooting Guide

Defrosting your freezer is an important part of fridge maintenance since it helps your fridge and freezer run more efficiently. While this might seem counterintuitive, a buildup of frost in your freezer will actually prevent your freezer from cooling your food properly. 

The majority of Bosch fridges have an automatic defrost feature that activates a couple of times a day, but if this defroster fails then frost might start accumulating in the fridge a lot more quickly. There are several parts of the automatic defrost system that can fail, but the most common points of failure are the defrost control board and defrost timer.

Today, we’ll be going over all of the major issues that can affect your freezer’s automatic defrost function, and explain how you can solve them.

Bad Defrost Timer

In a Bosch fridge with an automatic defrost feature, the defrost timer helps keep the defrost heater active for the right length of time, and shuts it off when the defrost cycle is done. If the defrost timer stops working, then the defrost heater will likely fail to activate at the right time.

To test the defrost timer, you’ll have to access it first. Depending on what model of fridge you have, the timer may be located in the control console inside the fridge, but it might also be behind the fridge’s bottom kickplate or on the back of the fridge.

If you’re not confident enough to partially disassemble your fridge and mess around with its electronics (which is totally understandable), you might want to consider hiring a licensed technician for this part. If you are confident enough, however, it’s pretty easy to test the timer once you find it.

There should be a dial on the timer that you can manually adjust. To test the timer, just turn it until it reaches the defrost cycle position. If the timer is working, you should hear the fridge compressor turn off and the defrost heater turn on. 

If you don’t hear this, it means the timer is defective and should be replaced. You should also replace the timer if the defrost cycle activates but doesn’t deactivate after the usual amount of time, as this can mean that the timer is not advancing properly.

Read: Your Fridge Is Not Cooling, Light Is ON? | How To Fix It

Failed Defrost Thermostat

The defrost thermostat keeps track of the temperature of the fridge’s evaporator coils, and activates when the temperature drops below a certain point. The thermostat has contact points that automatically close when the temperature gets cold enough, which in turn provides power to the heater.

If the thermostat isn’t working, the contact points might fail to close when it gets cold enough, and the heater won’t turn on. To test the thermostat, use a multimeter to see if it has any continuity when the temperature registered on the thermostat gets low enough. If it doesn’t have any, replace the thermostat. 

Read: Top Reasons Why Fridge Is Making Ice But Not Dispensing Water

Failed Defrost Heater

The defrost heater is, of course, what is actually responsible for defrosting your freezer. The defrost heater is usually located behind the back panel of your fridge’s freezer section.

To test the status of your defrost heater, you can once again use a multimeter to test it for continuity, and if it has none, it’s time to get a new heater. 

malfunctioned Defrost Control Board

The defrost control board is a circuit board and is essentially the brain behind the whole defrost system. The defrost control board is ultimately what tells all of the components of the defrost system to activate at the right time. If this board fails, the defrost system will be totally unable to work.

You should make sure to test the heater, thermostat, and timer before checking out the defrost control board since it’s a lot more likely that one of these parts is the source of the problem. If it is indeed the defrost control board, however, you’ll have to replace it.

Read: How Do You Know If Refrigerator Compressor Is Bad?

Bad Door Gasket

Having a broken seal around your freezer door won’t prevent your freezer from defrosting as such, but can cause a large amount of frost to accumulate inside your freezer and make the defrosting process a lot more difficult. 

This happens because it allows warm air to enter the freezer, and since warm air can hold a lot more moisture than cold air, it basically lets a bunch of water vapor get inside the freezer and subsequently freeze. Plus, since having a bad door gasket means your freezer is no longer sealed, it has to work a lot harder to maintain a cold temperature.

You can determine whether the door gasket is the source of your problem with a simple visual inspection. If the door gasket looks cracked or worn and feels brittle to the touch, it’s a sign that it probably needs to be replaced. 

Defrosting your freezer is an important part of fridge maintenance since it helps your fridge and freezer run more efficiently. While this might seem counterintuitive, a buildup of frost in your freezer will actually prevent your freezer from cooling your food properly. 

The majority of Bosch fridges have an automatic defrost feature that activates a couple of times a day, but if this defroster fails then frost might start accumulating in the fridge a lot more quickly. There are several parts of the automatic defrost system that can fail, but the most common points of failure are the defrost control board and defrost timer.

Today, we’ll be going over all of the major issues that can affect your freezer’s automatic defrost function, and explain how you can solve them.

Bad Defrost Timer

In a Bosch fridge with an automatic defrost feature, the defrost timer helps keep the defrost heater active for the right length of time, and shuts it off when the defrost cycle is done. If the defrost timer stops working, then the defrost heater will likely fail to activate at the right time.

To test the defrost timer, you’ll have to access it first. Depending on what model of fridge you have, the timer may be located in the control console inside the fridge, but it might also be behind the fridge’s bottom kickplate or on the back of the fridge.

If you’re not confident enough to partially disassemble your fridge and mess around with its electronics (which is totally understandable), you might want to consider hiring a licensed technician for this part. If you are confident enough, however, it’s pretty easy to test the timer once you find it.

There should be a dial on the timer that you can manually adjust. To test the timer, just turn it until it reaches the defrost cycle position. If the timer is working, you should hear the fridge compressor turn off and the defrost heater turn on. 

If you don’t hear this, it means the timer is defective and should be replaced. You should also replace the timer if the defrost cycle activates but doesn’t deactivate after the usual amount of time, as this can mean that the timer is not advancing properly.

Read: Your Fridge Is Not Cooling, Light Is ON? | How To Fix It

Failed Defrost Thermostat

The defrost thermostat keeps track of the temperature of the fridge’s evaporator coils, and activates when the temperature drops below a certain point. The thermostat has contact points that automatically close when the temperature gets cold enough, which in turn provides power to the heater.

If the thermostat isn’t working, the contact points might fail to close when it gets cold enough, and the heater won’t turn on. To test the thermostat, use a multimeter to see if it has any continuity when the temperature registered on the thermostat gets low enough. If it doesn’t have any, replace the thermostat. 

Read: Top Reasons Why Fridge Is Making Ice But Not Dispensing Water

Failed Defrost Heater

The defrost heater is, of course, what is actually responsible for defrosting your freezer. The defrost heater is usually located behind the back panel of your fridge’s freezer section.

To test the status of your defrost heater, you can once again use a multimeter to test it for continuity, and if it has none, it’s time to get a new heater. 

malfunctioned Defrost Control Board

The defrost control board is a circuit board and is essentially the brain behind the whole defrost system. The defrost control board is ultimately what tells all of the components of the defrost system to activate at the right time. If this board fails, the defrost system will be totally unable to work.

You should make sure to test the heater, thermostat, and timer before checking out the defrost control board since it’s a lot more likely that one of these parts is the source of the problem. If it is indeed the defrost control board, however, you’ll have to replace it.

Read: How Do You Know If Refrigerator Compressor Is Bad?

Bad Door Gasket

Having a broken seal around your freezer door won’t prevent your freezer from defrosting as such, but can cause a large amount of frost to accumulate inside your freezer and make the defrosting process a lot more difficult. 

This happens because it allows warm air to enter the freezer, and since warm air can hold a lot more moisture than cold air, it basically lets a bunch of water vapor get inside the freezer and subsequently freeze. Plus, since having a bad door gasket means your freezer is no longer sealed, it has to work a lot harder to maintain a cold temperature.

You can determine whether the door gasket is the source of your problem with a simple visual inspection. If the door gasket looks cracked or worn and feels brittle to the touch, it’s a sign that it probably needs to be replaced.