Sub Zero Freezer Not Working (5 Causes and Solutions)

Owning a Sub-Zero freezer signifies your kitchen excellence and promises years of reliable food preservation. With an average lifespan of 20 years, it’s a significant investment. But imagine reaching for your trusty freezer, only to be met with an unsettling silence. Panic sets in, and visions of spoiled groceries dance in your head.

However, fear not! While a malfunctioning Sub-Zero might seem like a kitchen nightmare, there’s often a simple solution at hand. In many cases, DIY troubleshooting can get your freezer humming happily again. This guide will walk you through common issues and potential fixes, empowering you to restore your frozen oasis and enjoy your Sub-Zero for years to come.

Why Is Your Sub Zero Freezer Not Working?

When your Sub Zero Freezer refuses to work, you may blame some common culprits, such as a faulty compressor, damaged door seal, or unclean condenser coils. However, some uncommon causes won’t make your list, such as control board malfunctions or refrigerant leaks. When any of these components strike, your Sub Zero Freezer witnesses a frosty meltdown.

Now, let’s explore these potential troublemakers and how to successfully troubleshoot them:

1a- Damaged Door Gasket

The door gasket of your Sub Zero freezer acts as a gatekeeper. It’s a rubbery seal lining the edges of the doors. It’s responsible for creating a tight seal that keeps the cool air inside where it belongs. A damaged or dirty gasket messes with the seal’s tightness, allowing the cold air to escape and leading Your appliance to work harder.

Additionally, a damaged gasket traps moisture inside the freezer, leading to frost buildup. Such a thing will gradually weaken the freezer’s efficiency.


1b- How To Fix Damaged Door Gasket

Whether you have a sub-zero refrigerator or a freezer, troubleshooting their faulty gaskets is similar. If you are certain that the door gasket is the silent saboteur in your Sub Zero Not Working situation, you should get a new one. Here are the troubleshooting tips to guide you while installing a new gasket:

  1. Unplug the freezer: This step helps you to dodge any electric shocks.
  2. Locate the gasket: You can easily find this component around the freezer’s door frame. Look for holding clips or a groove. Gently remove the old rubbery component.
  3. Clean the gasket: Don’t underestimate the power of dirt buildup. Stubborn buildup can hinder the installation of a new gasket. You can clean this component regularly to prevent the presence of dirt around the door seal. Use a damp cloth and soapy water to clear the frame of any buildup.
  4. Install the replacement gasket: Position the new gasket so that it aligns perfectly with the groove placement. Start with one corner and line the rest of the gasket with the door’s perimeter.
  5. Double-check the alignment: Bring a measuring tape to ensure that the new gasket aligns perfectly and evenly around the edges of your freezer’s door.

Freezer Door Not Sealing

 2a- Dirty Condenser Coils

Your Sub-zero Condenser coils reside in the freezer’s heart. They are responsible for releasing excess heat outside your freezer. This is how your Sub Zero refrigerator or freezer maintains cool and the stored food remains well-preserved.

The heat finds its way to these coils when the refrigerant flows through them. Then, it sheds heat to the surrounding air.

Besides the dust buildup, you can blame insufficient ventilation for this problem. Placing the freezer near a wall or in a poorly ventilated area can restrict airflow and trap heat, and may eventually hinder the coils’ function.

2b- How To Fix Dirty Condenser Coils

When trying to address the issue of unclean coils, make sure you prioritize your safety. So, disconnect the appliance from the wall outlet. Then, follow these instructions:

  1. Look for the coils:  They are located at the back of the unit behind a removable panel. Carefully and gently remove the holding screws using your flathead or Phillips head screwdriver.
  2. Use your vacuum cleaner: Use the nozzle or soft brush attachment and suck away any sort of debris or buildup. If this tool isn’t available, you can use a standard coil brush.
  3. Reattach the panel and try things out: Now that the coils are pristine, it’s time to reattach the removable panel and plug the freezer. Do the previous steps in reverse order and see if this fix works for you.

 3a- Malfunctioning Defrost Cycle

The main function of your freezer’s defrost cycle is to prevent frost buildup. The cycle starts periodically and automatically, melting accumulated ice into water. Every time this cycle kicks in, it frees the evaporator coils from ice buildup. This way, there will be efficient cooling and less energy waste.

But why would this cycle malfunction in the first place?

  1. A bad timer: This component controls the duration and frequency of the defrost cycle. But when it becomes defective, the cycle might become irregular or not start at all.
  2. A problematic defrost heater: This compact heater raises the temperature of the defrost system, which is required for triggering this cycle.
  3. Defective sensor: This sensor observes the temperature during the defrost cycle and signals its completion.

How to Prevent Ice Buildup In Freezer

3b- How To Fix Malfunctioning Defrost Cycle

While a problematic defrost system could be the culprit behind your Sub Zero freezer not working, it’s not always easy for all DIYers to diagnose and troubleshoot its components. So, if you don’t have the required repair skills, it’s recommended to seek professional help. But if you know your way with these electrical parts, you can do the following:

  1. Locate the defrost system: The components of this system reside at the back or the bottom of your Sub Zero freezer. Check your manual for specific information about the location.
  2. Find the timer: Look for the timer near the compressor. But before approaching this component with your screwdriver and multimeter. You should perform a test while the freezer is running.
  3. Make a quick test: Find the timer’s advance screw. Turn it clockwise until you hear a click. Wait about 35 minutes. Then, After the defrost cycle completes, it should allow the refrigerator to resume its normal cooling operation. If this doesn’t happen, it means you have a defective timer and need a new one.
  4. Test the defrost sensor: Find a round sensor with a plastic housing. Use your multimeter to perform a continuity test. Set the device to the ohms scale and connect one probe to each sensor wire. If the readings don’t match what you find in the guide, replace the sensor.
  5. Find the heater: In most Sub Zero freezers, the heater Looks like a coil of wire in a glass tube. Besides obvious signs of damage or corrosion, you can test this component with a multimeter to ensure its functionality. This test should result in readings other than zero or infinity.

4a- Defective Control Board

The main control board of your Sub Zero freezer is a tiny computer. It is responsible for regulating temperatures, managing the defrost cycle, and overseeing other essential freezer operations. However, even the most sophisticated brains can encounter malfunctions. If your freezer shows unstable or inconsistent temperatures or stops working altogether, the control board might be the culprit.

As a communication hub between the Sub Zero Freezer’s components, this board can malfunction due to many reasons, such as:

  • Power spikes or shorts: An unstable electrical supply can damage the control board’s delicate circuitry, affecting its ability to communicate with other components in your freezer.
  • Presence of moisture: If water finds its water in the control board’s housing, it can cause shorts or corrosion, disrupting its functionality.
  • Normal aging: Like all electronics, control boards have a lifespan. Over time, components can degrade, leading to malfunctions.

4b- How To Fix Defective Control Board

In most cases, no fix can revive your Sub Zero freezer’s control board. Replacing is the most convenient solution, but it is not cheap or easy for all DIYers. Before deeming the delicate board dead, you need to be certain of its malfunction.

If you are skilled and experienced enough to handle this delicate component, here’s what you should do:

  1. Cut off power: Unplug the freezer and open the back panel to access the control board.
  2. Gently detach the board: Disconnect the wires and screws that attach the control board to the appliance and carefully remove the board.
  3. Look closely: Inspect the board for any signs of damage, such as burnt components, broken connectors, or loose solder joints.
  4. Consider your options: If the board is damaged, you can either replace it with a new one or call in the pros. If you want a cheaper alternative, you can send it to a mail-in repair service. If you decide to buy a new board, locate the freezer’s model number by searching for the part number of the control board online. This way, you can get a compatible replacement part.
  5. Bring the board where it belongs: Install the new or repaired board in the appliance and reconnect the wires and screws.

 5a- Faulty Condenser Fan Motor

Inside your Sub Zero freezer, the condenser fan helps to remove the warm air from the refrigerant in the condenser coils. A faulty condenser fan motor can lead to several problems for your freezer, such as:

  • Preventing The refrigerant from flowing properly. Typically, the freezer interiors won’t be at normal temperatures.
  • The compressor will have to work harder and consume more power to achieve the desired temperature.
  • The freezer may produce loud noises or overheat due to the increased pressure and friction.
  • The freezer may break down completely if the compressor malfunctions or the refrigerant escapes.

 5b- How To Fix Faulty Condenser Fan Motor

This is a common appliance repair issue that can affect the performance and lifespan of your freezer. To fix a faulty condenser motor, you will need repair tools such as a screwdriver, a multimeter, and a replacement motor. Here are the steps to follow:

  1. Safety comes first: Unplug the freezer and remove the back panel to access the condenser fan motor.
  2. Clean the motor: Sometimes, the problem is as simple as an unclean component. You can easily resolve this issue by cleaning the motor and its surrounding area with a brush or a cloth. However, don’t scrap it using any sharp tools.
  3. Test the ohms: Use the multimeter to test the motor for continuity. If the motor does not have continuity, it is faulty and needs to be replaced.
  4. Detach the motor from the wires: Disconnect the wires and screws that hold the motor in place and remove the old motor.
  5. Bring the new motor home: Install the new motor and reconnect the wires and screws.


A Sub-Zero freezer not working can be frustrating, but there are solutions to get it back up and running. You may encounter various problems with your freezer, such as a damaged door gasket, dirty condenser coils, malfunctioning defrost cycles, defective control boards, or faulty condenser fan motors.

By following the troubleshooting tips provided in this article, you can fix these issues and restore your freezer’s functionality. Remember to prioritize your safety and seek professional help if needed. Don’t let a malfunctioning freezer ruin your groceries.

Take charge of your freezer’s performance and ensure its longevity. Follow these troubleshooting tips and fix your Sub-Zero freezer today!

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