In normal circumstances, a walk-in freezer defrosts regularly to remove ice buildup from the evaporator coils (the coils in the boxes on the freezer walls with fans) and keep the unit running smoothly. If it doesn’t defrost, the freezer and the evaporator coils and fans will ice up, leading to poor airflow, temperature fluctuations, and spoiled food. So, read this guide to know the causes of this problem and consult a commercial refrigerators repair expert for help.

When And What Happens In A Walk-In Freezer Cycle?

To remove ice buildup inside the unit, a walk-in freezer usually triggers an automatic defrost cycle 2-6 times a day, depending on the size, model, and settings of the freezer.

In a defrost cycle, the freezer stops cooling, the electric heaters (or any other heating system) turn on to remove ice buildup, and the melted ice (water) from the evaporator coil and the walls drains through the drain pan. This process takes about 15-45 minutes.

Causes of A Walk-in Freezer Not Defrosting

Failed Defrost Timer

A common reason for a walk-in freezer’s automatic defrost issues is a failed defrost timer. It’s like an alarm clock for the freezer to defrost at set intervals. It triggers the entire defrosting process and also the termination of the process.

If a defrost timer is faulty, it won’t signal the freezer to defrost, so it will keep cooling normally, which will lead to ice buildup. This is why many technicians inspect the defrost timer first and replace it if faulty.

Bad Electric Defrost Heater

The most common defrost method in most walk-in freezers with automatic defrost is electric defrost heaters. These are heating elements installed on or near the evaporator coil for melting ice buildup from it.

As these heating elements are the main tools that heat up to melt ice, if they malfunction, the defrost cycle won’t work. An expert usually tests the heating elements with a multimeter. If they are faulty, they are replaced.

Faulty Defrost Thermostat

A defrost thermostat or defrost limit thermostat is located in the evaporator coil housing. It monitors the temperature of the evaporator coil during the defrost cycle to make sure it doesn’t get overheated and also to save power and turn off the defrost cycle (the heating elements) when the ice melts from the evaporator coil.

A defrost thermostat can either fail in the open or closed positions. If it fails in the open position, it won’t let the defrost cycle turn on. So, ice will build up and cause problems. This can be the reason your walk-in freezer is not defrosting.

Moreover, if the defrost thermostat fails in the closed position, it won’t terminate heaters during defrosting when required. So, the heaters will keep running for longer, leading to damage to the evaporator coils and the unit.

Keep in mind that newer walk-in freezers may have a thermistor in place of a defrost thermostat. It also performs the same task and sends signals to the control board. The symptoms of a bad thermistor are similar to a faulty defrost thermostat.

Whichever component your walk-in freezer has, if it’s causing auto defrost problems, it must be replaced by a licensed commercial freezer repair Fairfax expert.

Incorrect Controller Settings

The defrost issue could simply be due to incorrect controller settings. Walk-in freezers and other similar refrigerant units have a controller that needs to be set optimally. Incorrect settings will lead to various problems, two of them are the defrost cycling not turning on or the defrost cycle running for longer than required.

Incorrect settings could be: defrost interval set too long or too short, defrost duration set too long or too short, wrong defrost termination temperature, wrong defrost type selection, and others. Consult a walk-in freezer technician who can check and adjust defrost settings. They may also check the components for problems.

If you already have the settings on the user manual, a log book, or something similar, you can simply view the settings yourself and make sure that they are correct.

Blocked Or Frozen Drain Lines

If your walk-in freezer’s defrost system is fine, it could be a blocked or frozen drain line creating the defrost not working problem. During a defrost cycle, ice melts and should flow through the drain lines. Any blockage due to food, debris, or a frozen drain line will lead the appliance not draining.

So, after the defrost cycle, when the freezer starts cooling, ice will build up quickly because of the un-drained water. This can block the evaporator coil and the fans with ice, causing cooling problems as well.

This is a problem you can inspect and fix yourself in most cases. Check the drain pan and drain line, and unclog or unfreeze them.

Door Gasket Problems

A door gasket is a combination of a plastic or rubber gasket with a magnetic strip. As the materials wear, the door doesn’t seal properly even when closed. Due to this, warm air keeps getting into the freezer. This moist air freezes inside the unit.

If the gasket leak is big enough, there will be more ice buildup inside the unit than normal. This will mess with the regular defrost functionality of the unit because the defrost cycles are set according to the requirements of the freezer without the factor of the ice buildup caused by the damaged gasket or door problems.

Therefore, the defrost system may come under stress because it won’t properly remove ice from the freezer. This can cause defrost system problems as well, on top of the gasket issue. So, have an expert inspect the door gasket of your walk-in and replace it if required.

Note that the same problem can occur if the freezer’s door is opened and closed too frequently or left open for long intervals.

Overloaded Freezer

Another problem that’s not related to the defrost system, but it can cause defrost and cooling problems, is improper storage practices. If the freezer is overstuffed with inventory, more than recommended by the manufacturer, there will be problems.

Many times, overstuffing can lead to food items or shelves blocking the fan and the airflow. With poor airflow, the freezer can’t keep the temperature at the required levels. There may be uneven temperatures and ice buildup on the evaporator coils.

Moreover, with an overloaded freezer, the defrost cycle may not function properly and fail to remove ice completely. This means that more ice will build up than defrosts.

Therefore, check the freezer and make sure that there are only the recommended number of items. Make sure that no food items or shelves are blocking the fans. Refer to the user manual or get advice from an expert on how much inventory you should keep in the freezer.

Electrical Problems

Apart from the defrost system’s components, there are many other electrical components that must work perfectly to ensure smooth and frequent defrost cycles according to the settings.

Electrical problems can include issues with the contactor, relay switch, fuses, wiring or connections, power outlet, circuit breakers, and others. Hire an expert who can inspect these components for problems when inspecting your walk-in freezer.

Conclusion

Defrost problems in a walk-in freezer can be due to incorrect settings, door gasket problems, a clogged drain, or an issue with the defrost system of the unit. For quick and effective troubleshooting, hire a walk in cooler repair Springfield technician.