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.

Why Is Bosch Refrigerator Not Defrosting?

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. 

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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. 

Read: Top 4 Reasons Why Your Fridge Leaking Water Inside


Now that we’ve discussed the issues that can affect your freezer’s defrost function, let’s take a minute to answer some of the questions you might have about defrosting your freezer.

How Long Should I Let My Freezer Defrost?

This depends on the method you use to defrost your freezer, and how much ice is inside it. If your freezer has an automatic defrost function, then the defroster will run automatically about every 8-10 hours, usually for around 30-45 minutes each time. You don’t have to remove any of the food from your freezer during this process either, which is extra convenient.

However, if you need to manually defrost your freezer, this can take anywhere from 2 to 24 hours depending on your methods and the amount of built-up ice that is present.  

Can I Use Hot Water to Defrost a Freezer?

If you’re looking to speed up the manual defrosting process, you can always try this trick with hot water. All you need to do is boil a pot of water, and leave it inside your freezer with the door closed. The heat and steam from the water will melt the ice a lot more quickly.

Don’t forget to place a bunch of towels inside your freezer to soak up all the meltwater, and also consider placing a trivet or something similar in your freezer to prevent the hot pot from damaging it. If it’s still taking too long, you can always reheat the water and try again. 

How Often Should I Defrost My Freezer?

If you have a freezer that requires manual defrosting, it’s a good idea to defrost it at least once a year. However, you may want to defrost it more often if you find that ice tends to accumulate inside fairly quickly. 

Regardless of how much time has passed, you should try and defrost your freezer whenever the layer of ice inside it gets thicker than about 1/4 of an inch or so.

What If I Never Defrost My Freezer?

If you never defrost your freezer, then obviously frost will start to build up inside it. As we’ve mentioned, however, too much ice in your freezer can actually prevent it from working properly.

This is because the excess ice can block the air vents in your freezer and prevent more cold air from being able to get in. When this happens, the freezer has to work extra hard to maintain the cold temperatures. Even if the freezer is still able to maintain the right temperature in this state, it will expend a lot more energy to do so.

There’s also the fact that ice takes up room that you could otherwise use to store food. This isn’t a big deal if there’s only a thin layer of ice present, but if you let the problem go on for too long, it can really rob you of a lot of freezer space.

Finally, if you never defrost your freezer, you run the risk of your frozen food going bad. So, unless you want your energy bills to skyrocket and you’re ok with all of your frozen food spoiling, you should always make sure to regularly defrost your freezer, or at least make sure the automatic defrost feature is working properly. 

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