Refrigerator Thermostat [How to, Issues & Proven Solutions]

A thermostat plays a vital role in how well a refrigerator works. This article discusses how to fix issues with a refrigerator thermostat and proven solutions to other problems.

Fridge Freezer Thermostat Refrigeration Temperature Controller Universal WPF-20

What Is a Refrigerator Thermostat?

A refrigerator thermostat is the part of the refrigerator that controls the internal temperature. You turn the thermostat’s knob to the setting you want, and the refrigerator begins to cool. It helps the refrigerator maintain a cool temperature for an extended period by its control of the electric power which the compressor receives.

How a Refrigerator Thermostat Works

A refrigerator thermostat keeps an eye on the internal temperature, turning the compressor off and on as needed. It does this task by cutting off the electricity flow to the compressor and other parts of the cooling system. 

You will find a capillary tube fixed to the thermostat, and the tube, which contains gas, works as a sensor. If the temperature rises, the gas in the tube expands and presses on a diaphragm. The diaphragm triggers contacts on the thermostat so that they close to allow power flow to the compressor. Once the temperature is low enough, the gas contracts and releases the diaphragm, and as a result, the contacts open to cut power from the compressor.

Adjusting a Refrigerator Thermostat – Steps

To adjust the thermostat in your refrigerator, take the following steps:

Step 1

Read the manual that comes with the refrigerator. Some thermostats use degrees, while others use numbers from 0 to 9 or 0 to 7. You can tell the recommended setting for the refrigerator and freezer compartments from the manual.

Step 2

Determine where you want to set it after consulting the manual. Then, turn the knob of the thermostat to the desired point. Wait about 24 hours to see the cooling capacity of the setting before determining if you need to adjust it lower or higher.

The recommended range on the manual may not be suitable for your specific needs. For instance, you may find that the setting should be 5 for a thermostat that works with numbers or 37 degrees Fahrenheit (4 degrees Celsius for degrees). But you may want it a little lower due to the refrigerator’s content.

Step 3

You may forget the correct temperature setting on the thermostat after a long time and constant use. Place a bottle of water in the refrigerator’s middle shelf and check its coolness after 24 hours. Its temperature will tell you which direction to adjust the thermostat – lower or higher. Another way to determine the correct temperature is to use a refrigerator thermometer.

Note that smaller numbers mean warmer temperatures in thermostats that use numbers. Higher numbers represent colder temperatures. Therefore, adjust the thermostat towards 0 or 1 if you want a warmer temperature or 6 or 7 for a colder temperature.

In addition, different sections of the refrigerator present varying temperatures. In other words, the refrigerator’s internal temperature is not uniform. The lower part tends to be cooler than the upper part and the door. The same is true in the freezer compartment. So, store foods according to their temperature need in the refrigerator and freezer.

Typically, a food-safe refrigerator temperature setting should be between 37 degrees and 44 degrees Fahrenheit. For the freezer compartment, the temperature setting should be between 0 degrees and 5 degrees Fahrenheit.

Re-calibrating a Refrigerator Thermostat

Locate the thermostat inside the refrigerator and disconnect its wires. Pull it down from the temperature control housing and find the two adjustment screws in front of it. The location of the screws may vary by refrigerator model, but you will find them on the thermostat.

You will need a small screwdriver to turn them. The screw on the left-hand side will change the thermostat’s cold-out. So, if your compressor turns on before the defrost cycle is over, you need to adjust the small screw on the left by turning it clockwise. But if the compressor takes time to resume operation after a defrost, turn the screw counterclockwise.

Test the temperature and defrost function of the refrigerator to determine whether or not you need to calibrate further. If you have exceeded the point you need on the thermostat, turn the screw slightly counterclockwise to move it closer to your desired setting.

This video is a demonstration of how to re-calibrate your refrigerator’s thermostat…

Refrigerator Thermostat Bypass – Steps

To bypass the thermostat in your refrigerator, especially when it is not cooling, do the following:

Step 1

Purchase an external thermostat and set it beside the refrigerator. Be sure to buy one that fits your refrigerator model. Open the door of the refrigerator and turn the knob of the thermostat to the coldest temperature setting. Then, disconnect the refrigerator from electric power and connect it to the external thermostat’s socket at the back.

Step 2

Insert the thermostat’s probe wire into the refrigerator. The wire is flexible and thin enough not to stop the closing or opening of the refrigerator door. So, secure it to the wall inside the refrigerator using duct tape. Then, close the refrigerator door.

Step 3

Connect the power cord of the thermostat to a wall receptacle to power it. You bypass the refrigerator’s built-in thermostat that may be faulty by doing this. Move the external thermostat’s knob to the setting you want or go low enough to cool the refrigerator quickly. If nothing else is causing the refrigerator’s cooling issues, the appliance should start cooling with the help of the thermostat as soon as possible.

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Refrigerator Thermostat Clicking – What to Do

The refrigerator may have a faulty relay on the adaptive defrost control. It is the device that supplies power to the compressor, controlling how much of it the compressor gets each time. The issue is that you may have a hard time replacing it yourself, so you may need the services of a qualified technician to do the job.

However, you must be sure that the clicking noise comes from the thermostat. The compressor may click on and off due to a heat overload. Dirty condenser coils and an inoperative condenser fan cause the compressor to shut down under the burden of excessive heat. So, you may hear it clicking as it shuts down and tries to restart.

If the sound comes from within the refrigerator, it may be the thermostat. But it is the compressor if it comes from the bottom back of the refrigerator.

What Causes a Refrigerator Thermostat to Fail?

A refrigerator thermostat may fail if the gas in the capillary tube depletes. It is a mechanical fault that requires you to replace the thermostat. Another possible cause of a failed refrigerator thermostat is loss of connection or damage to the connectors between the thermostat and the refrigerator. The contacts may also break, causing the thermostat to stop working. Replace the thermostat if any of the above applies.

How to Test a Refrigerator Temperature Control Thermostat

To test the temperature control thermostat in a refrigerator, you may need the refrigerator’s wiring diagram. It may be in the compartment for the compressor or taped to the refrigerator’s back. You will see the wires that go from the temperature control thermostat to the compressor from the chart. Disconnect the wire harness and get a multimeter.

Set the function of the multimeter to a scale of RX1 and connect the thermostatic switch’s wires to the multimeter’s probes. When the thermostat is switched off, the display on the meter should be O.L. slowly turn the thermostat’s knob and observe the meter’s display; it should change to 0.000 as the thermostat nears its coldest setting. If the multimeter registers 0.000 when the thermostat is off or shows O.L when the thermostat is at the coldest setting, replace the thermostat.

The refrigerator may run non-stop even when the thermostat seems to be in good working condition. That means another component is causing the problem. It may be that the temperature control sensing bulb is faulty. Since you cannot replace the bulb alone, you may want to replace the entire temperature control.

Other Ways to Check a Refrigerator Thermostat

You will know the refrigerator thermostat is defective if the refrigerator does not stop running. It may be that the thermostat does not turn off, thereby keeping the compressor from turning off. Consequently, it freezes everything in it, even though a refrigerator temperature does not permit freezing. 

Also, ensure the condenser coils are not excessively dirty and the condenser fan is working. These two parts can trigger the compressor to run non-stop because they cause the refrigerator’s temperature to rise.

Another tell-tale sign of a faulty thermostat is a refrigerator that is not cooling enough or at all. Just like the thermostat can trigger the compressor to run without stopping, it can also cause the compressor not to run enough or at all. It does this by not supplying enough power to the compressor.

In the case of too much cooling or no cooling, adjust the setting of the thermostat to a lower or higher setting. Then, give the refrigerator about 24 hours to adjust to the temperature before determining whether or not you need a new thermostat.

Refrigerator Defrost Thermostat Test

To test the defrost thermostat in a refrigerator, disconnect the refrigerator from electric power. Locate the thermostat on the evaporator coils and run a test on it with a multimeter to see if it has continuity. Replace the defrost thermostat if there is no continuity.

A defective defrost thermostat can cause a refrigerator to run constantly. The thermostat should turn the defrost heater on and off during a defrost cycle. But when it fails, the heater may not turn off, causing a rise in the internal temperature.

How to Reset a Refrigerator Thermostat

To reset the thermostat in your refrigerator, unplug the appliance from the power source. Then, turn the knob of the temperature control to zero or Off. then, plug the refrigerator’s power cord back into the wall outlet and turn on the temperature control by adjusting it to your desired temperature setting. Give the refrigerator 24 hours to adapt to the new temperature setting.

How to Change the Thermostat in a Refrigerator

Take the following steps to change the thermostat in a refrigerator:

Step 1

Disconnect the refrigerator from electric power and find the thermostat. You may find it under the unit for top or bottom freezer models. But for side-by-side models, the thermostat may be fixed to the refrigerator’s back.

Step 2

Loosen the screws or release the clips that secure the cover panel over the thermostat so that you can remove it. Keep the cover and screws or clips in a safe place.

Step 3

Gently pull off the wire harnesses on the thermostat using a needle-nosed plier. In some models, you may find pin terminals in the place of harnesses. Follow the same process. Next, unmount the clip or screw that secures the thermostat to the evaporator coils and slide it off.

Step 4

Slide the new thermostat onto the evaporator coils and secure it with the clip or screw. Connect the pin terminals or wire harnesses to the thermostat and replace the cover. Secure the cover with screws or clips, depending on the model.

Reconnect the refrigerator to electric power and wait for it to cool considerably. That way, you know the thermostat is working. Otherwise, you may want to retrace your steps to see if you made all the right connections. If you are not sure, hire a certified technician to find the fault.

Recap

One of the most important parts of a refrigerator’s cooling ability is the temperature control thermostat. A faulty refrigerator thermostat cannot keep the unit up and running since it supplies power to the cooling system. Therefore, it is crucial to check the thermostat, among other things, if you notice your refrigerator is no longer cooling.

Some repairs will need a qualified technician, especially if it involves live voltage. If it does not require electricity to repair, be sure to disconnect the refrigerator from electric power before commencing repairs. Hire a professional for the repair job if you find it too difficult.

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