Sub-Zero Freezer Not Freezing [Solved]

This article deals with how to handle a Sub-Zero freezer that is not freezing. So, read this article to learn the different ways to fix it.

Sub-Zero freezer not freezing
Photo Credit: Kowloonese, (under license)

Sub-Zero Freezer Not Freezing – How to Fix

If your Sub-Zero freezer is not freezing, check the following freezer parts for fault:

1. Start Relay

Run a test of the continuity of the relay between the start and run terminals. If you don’t find continuity, replace the start relay. Additionally, if the start relay has a burnt smell, replace it.

Since the compressor powers the freezer, the freezer cannot get cold or freeze if the compressor doesn’t run. And the compressor may not run if the relay is bad.

2. Evaporator Fan Motor

Check the motor of the fan by opening the door of the freezer and activating the door switch. Usually, doing this will get the evaporator fan running again even if the door is open because if you open the door of the freezer, the fan automatically stops running.

However, if you activate the switch and the fan does not run, then the motor is faulty. It needs to be replaced.

The freezer cannot get cold or freeze if the evaporator fan doesn’t run. And the fan cannot run if the motor is faulty.

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3. Condenser Coils

If your freezer is the type that has the condenser coils inside the walls of the freezer, then there’s no need to clean them. But if you can easily see them behind or under the freezer, check to see if they are dirty. Clean them thoroughly if they are and repeat the cleaning process every 6 months.

Dirty coils mean the freezer will carry the heat from the refrigerant that passes through them. The refrigerant will carry the heat into the freezer and reduce its capacity to cool.

4. Condenser Fan Motor

Try to spin the blades of the condenser fan with your hand. If they stiffly spin, then be aware that the bearings of the motor of the fan are worn. So, the motor needs a replacement.

However, if there is no stiffness when you spin them and nothing else is obstructing the blades, check the motor for continuity using a multimeter. If you don’t find continuity, replace the motor as soon as possible.

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5. Evaporator Coils

The evaporator or cooling coils are responsible for releasing cold air so that the evaporator fan can blow it into the freezer. So if they have frost on them, they will not be able to perform optimally. Consequently, there will likely be no cold air in the freezer.

Check for frost on them. Defrost the frost with a safe heat source or by defrosting the freezer manually. And if the coils are dirty, clean them thoroughly.

It is important to note here that for frost to build on the evaporator coils, one or more components of the defrost system has failed.

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Test the defrost heater with a multimeter to see if there is continuity. Replace the heater if there is none.

If nothing is wrong with the defrost heater, then check the defrost timer. Turn it with a flathead screwdriver counter-clockwise and wait to see if the heater comes on. If the heater comes on, then the timer is defective and should be replaced.

You can also check the defrost thermostat to see if it is defective. If it is, it cannot allow the defrost heater to come on when it senses that the cooling coils are cold enough to be warmed by the heater.

Another important thing to note is that if frost builds on just a part of the evaporator coils, you may have a sealed system leakage or freon issue on your hands. Have a qualified refrigerator technician take a look at the freezer and advise you on what to do.

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6. Temperature Control Thermostat

Moving the thermostat to the highest setting from whichever point it is will cause a clicking sound. That sound tells you that the thermostat is working properly. But if the clicking sound does not come, check for continuity using a multimeter. If there is no continuity, the thermostat needs a replacement.

Without the temperature control thermostat, the fan motors and the compressor will not have the needed voltage to run. As a result, the refrigerant won’t run and the freezer won’t cool.

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You can apply all the corrective steps for a Sub-Zero freezer that is not freezing to all models and types of Sub-Zero freezers. These include the fridge freezer, the bottom-drawer freezer, the top-freezer and the chest freezer.

Quick Note

If your Sub-Zero freezer is not freezing and you want to perform a diagnostic or repair work on it, unplug it from the wall outlet. You can also switch the circuit breaker for the freezer off if you cannot easily reach the wall outlet. This is the first safety step in electronic repair work.


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