Thermostat in the refrigerator: device, location and fault diagnosis

Stable operation of the refrigeration chamber directly depends on the serviceability of one small but critical element - the thermostat. It is this component that is responsible for maintaining a given temperature regime, opening and closing the electrical circuit of the compressor at the right time. If you notice that the refrigerator has stopped turning off or, conversely, has stopped freezing, the first thing you should pay attention to is the condition of the thermostat.

In this article we will look in detail at how it works thermostat, where it is usually hidden in various models of household appliances and how to independently carry out initial diagnostics. Understanding the operating principle of this unit will allow you to save time on troubleshooting and avoid unnecessary expenses on calling a technician for the simplest cases.

Understanding the design of the temperature control system is not as difficult as it might seem at first glance. We will look at the main signs of breakdown, methods for checking the serviceability of the part and replacement nuances that every owner of modern refrigeration equipment should know.

The principle of operation of the thermostat

The main task of the thermostat is to automatically control the temperature inside the refrigerator chambers. Structurally, a classic mechanical thermostat is a sealed system filled with a sensitive gas or liquid. This system is connected to a bellows (corrugated tube) that responds to changes in pressure inside the capillary tube.

When the temperature in the evaporator increases, the gas in the capillary tube expands, increasing the pressure on the walls of the bellows. This pressure is transmitted to the actuator, which closes the contacts and starts compressor. The reverse process occurs when the specified lower limit is reached: the gas is compressed, the bellows is compressed, and the circuit opens.

⚠️ Attention: In models with electronic control, the operating principle is different. There, instead of gas, thermistors are used, changing their resistance depending on the temperature, and the signals are processed by the central control module. Thermistors The accuracy of the device depends on the quality of calibration and the tightness of the system. If a microcrack occurs in the capillary tube, the gas will evaporate and the thermostat will stop responding to environmental changes. This is why thermistors (thermistors) that change their resistance depending on temperature, and the signals are processed by a central control module.

The accuracy of the device depends on the quality of calibration and the tightness of the system. If a microcrack occurs in the capillary tube, the gas will evaporate and the thermostat will stop responding to environmental changes. That's why mechanical damage to the capillary tube during defrosting often leads to a complete stop of the refrigerator.

Where the thermostat is located in different models

The location of the thermostat greatly depends on the type of refrigerator, year of manufacture and manufacturer. In old Soviet-made models or early imported versions, the sensor was most often located inside the refrigerator compartment. In modern units, engineers strive to hide technical components in order to improve aesthetics and ergonomics.

In most two-chamber refrigerators with mechanical control, the thermostat is located under a plastic cover on the inner wall of the chamber or in a special plastic casing next to the temperature controller. In models with the system No Frost access to it can be difficult, since it is often hidden behind the rear panel or in the ceiling of the refrigerator compartment.

Let's consider the main placement options:

• 📍 Inside the chamber: Next to the light bulb or under the temperature control knob. Typical for the Atlant, Biryusa and old Indesit models.
• 📍 Outside the chamber: In a niche above the door or in the upper part of the case. Often found in Stinol refrigerators and some Leran models.
• 📍 In the electronic unit: There may not be a separate mechanical thermostat; its function is performed by a sensor built into the common wiring harness.

If you are looking for where located thermostat in your refrigerator, pay attention to the power adjustment knob. The axis on which it is mounted usually passes through the body and connects directly to the thermostat mechanism.

Hidden installation locations

In some models of Samsung and LG refrigerators, the thermostat can be located in a technical box at the top of the refrigerator, accessible only after removing the decorative ceiling panel cameras.

Main signs of a malfunctioning thermostat

Diagnostics begins with observing the behavior of the refrigerator. A faulty thermostat disrupts the normal operating cycle of the compressor, which immediately becomes noticeable by indirect signs. Ignoring these symptoms can lead to spoilage of food or failure of a more expensive unit - the motor.

The most striking symptom is that the refrigerator works non-stop. The compressor hums constantly, trying to catch up with the temperature, but the shutdown command is not received. This indicates that the contacts inside the thermostat are “stuck” in a closed state or the capillary tube has lost its tightness.

The opposite situation is also possible: the refrigerator is silent and does not turn on, although there is voltage in the socket and the light is on. In this case, the thermostat contacts do not close, and electric current does not flow to the engine starting relay. Sometimes to start it is necessary to forcibly close the contacts or knock on the regulator.

Other alarm signals:

• ❄️ Excessive freezing: A “coat” of ice forms in the refrigerator compartment, food in the vegetable drawers freezes.
• 🌡️ Unstable temperature conditions: Temperature jumps, the products either thaw or become covered with frost.
• 🔌 Short cycles: The compressor turns on for 2-3 minutes, then turns off for a long time.

⚠️ Attention: If the refrigerator runs non-stop, it puts excess stress on the compressor. Long-term operation in this mode can lead to thermal overheating of the windings and motor wedge, repair of which is often unprofitable.

Instructions for checking the thermostat with a multimeter

For accurate diagnosis you will need a simple a multimeter configured for continuity or resistance measurement mode. Before starting any work, be sure to disconnect the refrigerator from the power supply. Safety is the number one priority when repairing household appliances.

First you need to remove the thermostat. Remove the regulator handle, unscrew the fastening screws and remove the device body from the seat. Disconnect the wires after first remembering or photographing their connection diagram. Typically, three or four wires go to the thermostat.

The test process is as follows:

1. Connect the multimeter probes to the contacts that go from the network and to the compressor.
2. In normal conditions (at room temperature), the circuit should be closed and the device should show zero or make an audible sound signal.
3. To check the open circuit, you can cool the sensitive tube (place it in the freezer for 10-15 minutes), after which the resistance should increase to infinity.

If the multimeter shows a break (one on the screen) at room temperature, it means thermostat it is faulty and requires replacement. It is also worth checking the resistance between the contacts and the case - there should not be any, otherwise a breakdown on the case is possible.

Compatibility table and markings

When selecting a spare part, it is important to take into account not only the dimensions, but also the temperature range of operation. Different manufacturers use different labeling systems. Below is a table of correspondence between popular thermostat models for various brands of refrigerators.

Please note that the length capillary tube is critical. If you buy a thermostat with a shorter tube, it may not reach the evaporator and the adjustment will be incorrect. A tube that is too long can be carefully rolled into a ring, but must not be bent or shortened.

Replacing a thermostat with your own hands

The process of replacing a thermostat is technically simple, but requires care. The main rule is not to damage the capillary tube of the new device. It is very thin and breaks easily if handled carelessly. Carry out all manipulations smoothly, without sudden jerks.

Install the new thermostat into the seat, secure it with screws and connect the wires strictly according to the previously made diagram or photograph. Pay special attention to the grounding wire (usually yellow-green), which is attached to the thermostat housing to protect against voltage breakdown.

After assembly, turn on the refrigerator and set the regulator to the middle position. During the first hours of operation, the device can work in enhanced mode, gaining temperature. Do not load the chamber with products right away - let the system enter the operating cycle.

If after replacement the nature of the refrigerator’s operation has not changed, the problem may lie deeper. Perhaps the start relay itself is faulty or there is a freon leak. In such cases, it is recommended to contact a professional technician for a more in-depth diagnosis. compressor, start relay or a freon leak has occurred. In such cases, it is recommended to contact a professional technician for a more in-depth diagnosis.

Is it possible to repair an old thermostat?

Theoretically, disassembling and cleaning the contacts is possible, but in practice this rarely gives long-term results. A broken bellows seal or a change in gas properties renders repairs useless. It is easier and more reliable to buy a new part, the cost of which is usually low.

Why does the new thermostat click more often than the old one?

The frequency of clicks depends on the sensitivity of the new device and the condition of the door seals. If the door does not close tightly, the temperature will rise faster, causing frequent startup. Also, the new thermostat may have a more accurate (narrow) response range.

Does the system need to be evacuated when replacing the thermostat?

No, the thermostat is located outside the refrigerant circuit. The capillary tube is only inserted into the evaporator channel or attached to it from the outside. Replacing the thermostat does not require opening the freon circuit and filling with gas.