How to diagnose and replace a refrigerator thermostat with your own hands?

With the right tools and a methodical approach, replacing and diagnosing a refrigerator thermostat can save you money and time. In order to keep your food fresh, the thermostat in your refrigerator is essential for controlling the temperature inside. The thermostat may be broken if you observe irregularities in the cooling process, such as objects freezing in the refrigerator or food not cooling down sufficiently.

Make sure you are safe before beginning any repairs by unplugging the refrigerator from the power source. Usually found inside the refrigerator, close to the cold control mechanism, is the thermostat. It’s a tiny gadget that senses temperature and turns on the compressor to keep the cooling at the proper level. The control knob, which frequently hides clips or screws holding the thermostat cover in place, should be removed first.

After you’ve gained access to the thermostat, test its operation with a multimeter. Touch the thermostat’s terminals with the meter probes after setting the multimeter to the ohms setting. When the temperature drops, a working thermostat should display continuity (almost no resistance) and infinite resistance (warm resistance). The thermostat probably needs to be replaced if the readings don’t correspond with these requirements.

Disconnecting the outdated thermostat from its wiring harness is necessary before replacing it. To guarantee that the new thermostat is installed correctly, snap a picture or write down the wiring layout. Take care when separating the cables to prevent damaging the wiring or connectors by not using too much force. Reconnect the wires to the appropriate terminals on the new thermostat in accordance with your notes or the attached photo.

Replace the cover and fasten it with screws or clips once the replacement thermostat is connected. Replug the refrigerator back into the power outlet and reattach the control knob. After adjusting the thermostat to the desired setting, watch how well the refrigerator cools over the next several hours. Without hiring a specialist, you can prolong the life of your refrigerator and increase its efficiency with this do-it-yourself repair.

Signs of a broken temperature relay

A thermal relay failure can be indicated by several signs:

• violation of cyclicity in the operation of a household appliance (the unit operates for a long time without switching off on its own);
• rapid growth of a layer of frost in the freezer, the appearance of ice in the refrigerator compartment;
• The electrical device does not turn on for a long time.

These issues could point to a relay malfunction or be the result of other issues with the refrigerator (e.g., leaks of refrigerant, motor failure, failed door seals, etc.).

Snow coat in the freezer

If there is a noticeable layer of frost on the freezer’s walls, make sure the temperature mode is set appropriately and examine how tightly the chamber door seal is sealed. In the unlikely event that everything is in working order, a thermal relay malfunction is likely.

The malfunctioning sensor fails to notify the refrigerator compressor’s start relay that the cooling cycle needs to be finished after the freezer temperature has been set. The evaporator is pressed for time, the motor keeps running, and the chamber rapidly fills with a layer of snow.

Ice may form in the freezer and refrigerator sections of the refrigerator if it has two thermostats and separate temperature controls for each compartment.

Disconnected and silent

Causes of the refrigerator’s shut-off:

• external factors (for example, loss of power due to a power surge, faulty socket, plug or cable);
• breakdown of the engine start relay, electric motor;
• thermostat failure.

When the temperature inside the refrigerator compartment rises, a broken relay does not react by sending a signal to the start relay, which prevents the motor from starting.

The total lack of any noise, sounds, or clicking in the refrigerator—signs that something is trying to turn on the motor—is indicative of a broken thermostat.

Doesn"t turn off on its own

The compressor runs in a cyclical manner, turning off after 10 to 20 minutes and then restarting the system’s freon circulation (read more about the features of manually filling a refrigerator with freon here). The device can work for a slightly longer period of time during the hot season, but not continuously.

A malfunctioning thermostat could be the cause of the unit’s failure to shut down, in addition to breaking the regulations regarding using home appliances, having a loose door fit, having a malfunctioning start-up relay, and having a refrigerant leak. The thermostat stops signaling when the compressor needs to be stopped. The motor overheats and fails because it keeps running without stopping.

How to replace a temperature sensor yourself?

It’s possible to identify a breakdown and fix the refrigerator on your own; however, you’ll need to perform some diagnostic work before replacing the unit in order to accurately determine whether a malfunctioning thermostat is the source of the issues.

Diagnostics and adjustment

Use the following technique to verify that the functional unit is operating if the freezer’s walls are noticeably frozen:

1. While the motor is running, slowly turn the control knob to increase the temperature inside the compartment.
2. After some time, when the level of the set value coincides with the temperature level in the compartment, the sensors will record the set parameter and the compressor will receive a shutdown signal. Stopping the motor will mean that the relay is working properly.
3. Remove all food from the chamber and leave the refrigerator on for 5–6 hours. During this time, carefully monitor the duration of breaks in the operation of the motor: if it is at least 30–40 minutes, the household appliance can be operated as usual. Otherwise, adjust the cyclicity of the compressor by changing the thermostat settings.

If you run the engine while adjusting the relay knob and raising the chamber’s temperature, the regulator is broken and has to be replaced.

Here’s how to figure out that the thermostat is the "culprit" behind the refrigerator not being turned off:

1. disconnect the refrigerator from the power supply;
2. remove all products and place them in a cool place while checking the functional unit;
3. set the regulator knob to the lowest possible temperature or turn on the freezing mode;
4. place a thermometer on the middle shelf of the refrigerator compartment that can measure air temperatures below 0 ⁰C;
5. connect the refrigerator to the power supply;
6. after 2 hours, evaluate the thermometer readings: if the air in the refrigerator compartment is heated to more than 6 ⁰C above zero, the relay is faulty.

Try these steps if the household unit doesn’t start up again quickly after being turned off:

1. Turn off the power supply to the refrigerator, remove the thermostat housing. In older refrigerator models, two wires are connected to the terminals of the functional unit. Disconnect them and directly connect them to each other (with a small piece of wire or an unbent paper clip). If the compressor starts working when the contacts are closed, the relay is not suitable for operation. If the motor does not start, the cause of the malfunction may be a breakdown of the starting relay or motor.
2. In more modern models of household refrigerators, 4 wires are connected to the thermostat:
3. yellow with a green stripe – grounding;
4. orange (or red, black) connects the unit to the compressor;
5. brown – "zero", leads to the plug;
6. white (or yellow, green) is connected to the light bulb in the refrigerator chamber.

Short-circuit every wire but grounding to find a malfunctioning thermostat. The regulator is broken if the motor turns on.

With a digital multimeter, you can check the unit more precisely. Just take out the relay, submerge the bellows tube’s end in cold water for one to two minutes, flip the switch to the resistance measurement mode (the "200" position), and take readings. The thermostat needs to be changed if the tester screen displays the number "1."

Tools

You will need the following to fix the refrigerator on your own (replace the regulator):

• flat and Phillips screwdrivers;
• knife;
• round nose pliers;
• spare element of suitable modification.

Rules for dismantling the thermal relay

The thermostat on older refrigerator models is housed inside the unit. Disassembling the protective plastic case and temperature control knob is required in order to extract the element. The thermostat in a more contemporary refrigerator is often placed above the door in the upper section, outside the chamber.

Taking the defective part out:

1. Remove the element protective cover.
2. Disconnect the capillary tube from the evaporator, carefully remove it from the housing.
3. Unscrew the fixing bolts and remove the relay. The block with contacts and regulator can be mounted either with screws or with latches.
4. Disconnect all terminals with wires that are connected to the thermostat. To avoid confusion with the connection when installing a new part, write down the color coding of all wires.
5. Remove the faulty element from the refrigerator.

Disconnect the power supply to the home appliance before replacing a working unit.

Replacement

1. Carefully, so as not to damage the part, insert the new bellows tube into the housing and attach it to the evaporator. The part must be pressed against the wall of the element.
2. Connect the relay wires.
3. Reinstall the working thermostat.
4. Secure the protective cover, all panels and components that were removed when dismantling the assembly.
5. Connect the refrigerator to the power supply.

Control the refrigerator’s operation within two to three days of the relay being replaced. If the temperature regime deviates from the predetermined range, further thermostat power sprunk adjustment (tightening or loosening) may be necessary.

If done methodically, diagnosing and replacing a refrigerator thermostat can be a simple task. Begin by recognizing typical signs such as uneven refrigeration or a warm refrigerator section. These symptoms frequently point to thermostat problems. Unplug the refrigerator and locate the thermostat (usually located behind the temperature control panel) to start your diagnostic.

Once it’s located, check the thermostat for continuity with a multimeter. To do this, touch the probes to the thermostat’s terminals and set the multimeter to the resistance or continuity setting. When the thermostat is cold and there is no continuity, it probably needs to be replaced. For specific testing instructions applicable to your model, make sure to refer to the handbook or internet resources that came with your refrigerator.

Make sure to unplug the refrigerator entirely before replacing the thermostat. The thermostat can be carefully disconnected from its wiring and removed from its housing after the control panel covering it has been removed. Before installing the new thermostat, make a note of the wire locations or snap a photo for your records.

Reverse the removal procedures to install the new thermostat. Make sure the wires are securely fastened by connecting them to the correct terminals on the new thermostat. After installation, put the cover back on the control panel and restart the refrigerator. Make sure the cooling problems are resolved by replacing the thermostat by keeping an eye on how the refrigerator operates.

It’s always best to consult a professional technician if you’re uncomfortable or unsure about any aspect of diagnosing or replacing the thermostat. Proper diagnosis and installation are essential to preserving the lifespan and efficiency of your refrigerator.

We’ll take you step-by-step through the methodical process of independently diagnosing and replacing a refrigerator thermostat in this guide. A broken thermostat can cause problems like uneven cooling or extremely low temperatures, which can impact the freshness of your food and increase your energy costs. You can ensure your refrigerator runs effectively and dependably by doing this repair yourself, saving money and time by learning common symptoms and using simple tools.

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