undercounter Refrigerators

How To Diagnose Your Undercounter Sub-Zero Refrigerator?

How To Diagnose Your Undercounter Sub-Zero Refrigerator?

Because of how they can be installed seamlessly into virtually any kitchen without taking up any additional space, undercounter refrigerator are often a top choice for homeowners. However, while Sub-Zero refrigerators are known for being extremely reliable, it’s not uncommon to occasionally run into issues, especially as your appliance ages over the course of the years. With that in mind, below, we’ll go over a few simple troubleshooting steps that can help you diagnose your problem and get your unit back up and running again!

Undercounter Sub-Zero Refrigerator

Temperature Issues

Whether we’re talking about a refrigerator that’s either too warm or too cold, it’s equally frustrating. However, temperature issues are typically easily resolved. 

Evaportator Fan Motor

If you notice that your refrigerator isn’t cooling as efficiently as it once did, it might be caused by a faulty or malfunctioning evaporator fan motor. To check this, open your fridge door and listen to see if you can hear the fan running. This fan is responsible for circulating cool air throughout the unit. However, it’s not uncommon for the fan motor to wear out and breakdown over time.

Refrigerator Evaporator Fan Motor

Temperature Control Thermostat

In some cases, your unit’s thermostat may be faulty, which could be the source of your problem. 

However, before you start taking things apart to try and diagnose this, first check that the thermostat is, in fact, set to the correct temperature. 

In many cases, the thermostat may be changed accidentally, which could be why your fridge is either too warm or too cold. 

temperature control thermostat

Start Relay

Next, a refrigerator that isn’t cooling properly may result from a faulty compressor start relay. The start relay is the component that tells the compressor when it needs to starter working and when to turn itself off. If your start relay is bad, you’ll often hear a clicking or ticking noise while your compressor is running. However, to diagnose and resolve this issue, you’ll need to take some of your unit’s components apart. So if you’re unsure how to do this, don’t hesitate to contact a professional appliance technician today. 

Start Reply refrigerator

Noisy Refrigerator

There’s nothing worse than when you hear your appliance making unusually loud noises. Unfortunately, many internal components might be malfunctioning and causing this issue. The two most common are damaged or broken fan blades or a malfunctioning compressor. 

Damaged Fan Blade

Start by unplugging your unit, and, if possible, locate your evaporator fan to check to see if you can see any visible signs of damage and manually turn the fan blades by hand.Even if the fan blades turn, but you can feel a great deal of resistance, this likely indicates a broken bearing, which will need to be replaced before the unit will work properly.

Fan Blade refrigerator

Malfunctioning Compressor

Your unit’s compressor is the component responsible for pumping coolant through the condenser coils. When the compressor starts to malfunction or breaks, it’ll often result in the loud or unusual noise you hear. 

Malfunctioning CompressorMalfunctioning Compressor
Need help diagnosing a noisy refrigerator? Don’t hesitate to contact us today!

Refrigerator Won’t Defrost

When your unit doesn’t defrost properly, this will often result in a buildup of ice or condensation inside your unit and on your condenser coils. 

Both of which can easily leave you with a headache that I’m sure you’d rather live without.

Defrost Timer


A refrigerator’s defrost timer will tell the defrost system when to kick on at predetermined intervals. This works to ensure that there won’t be any frost buildup whatsoever since the unit will periodically do this independently. Therefore, if the timer is faulty, the whole defrost system won’t work. To diagnose this, you’ll need to use a multimeter to test for continuity. This can be done at home by yourself. However, we recommend contacting us for help, ensuring that your unit’s warranty will remain intact.

Sensor With Fuse

Sensor with fuse refrigerator

With some Sub-Zero units, the defrost system might have its very own fuse. In the event of a power surge or a short-circuit, this fuse might burn out, which will prevent the rest of the defrost system from working properly. You can try using your unit’s owner’s manual to locate the defrost sensor fuse, or if you’d rather, feel free to contact us today for professional appliance help near you.


thermostate refrigerator

When the inside of your unit reaches a certain temperature, the defrost thermostat tells the system to start warming up and defrosting your coils. Therefore, if this thermostat is broken or faulty, the unit won’t know when to start or stop, resulting in excessive frost buildup. 

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Sub-Zero Appliance Repair Near You

Whether you're looking at installing, repairing, or simply maintaining your Sub-Zero or Wolf appliance, it's important only to do so if you're completely sure of what you're doing. If not, you risk causing other damages to your unit, which could potentially void your warranty. Therefore, to ensure that your repair or maintenance jobs are done properly and promptly, don't hesitate to contact us today. We know Sub-Zero appliances inside and out, which means that we'll be able to get your unit back up and running in no time at all!

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