The situation when the refrigerator stops correctly maintaining the temperature regime often causes panic among owners of household appliances. If the compressor runs without stopping or, conversely, does not turn on at all, the temperature regulator becomes the first suspicious element. In refrigerators LG this unit can be implemented differently depending on the year of manufacture and model series. Understanding exactly where this important component is located is a key step before starting any diagnostics or repairs.
In modern devices of the Korean brand, the classic mechanical thermostat is becoming less and less common, giving way to electronic sensors. However, the principle of their operation remains similar: they control the temperature inside the chambers and send a signal to the control board or directly to the compressor. Localization of the element depends on the design of the evaporator and the type of defrosting system. In older models, you need to look for a mechanical “box” with a tube, and in new ones, small electronic components mounted on the walls or hidden in the casing.
Before disassembling the unit, you need to clearly determine the type of control of your device. If the front panel has a digital display and buttons, then it is most likely installed inside electronic sensor. If the adjustment occurs by turning the knob inside the chamber, then we are talking about a mechanical thermostat. This fundamental difference will determine the search strategy and the required set of tools. An error in determining the type of regulator can lead to unnecessary disassembly of panels and loss of time.
⚠️ Attention: Before starting any work to search for internal components, be sure to disconnect the refrigerator from the electrical network. Working with live electrical wiring and metal elements is deadly.
Differences between mechanical and electronic regulators
Searching for a thermostat in a refrigerator LG is impossible without understanding the fundamental difference between mechanical and electronic systems. A mechanical thermostat is a sealed capsule of gas or liquid connected to a long sensing tube (bellows). As the temperature changes, the gas inside the tube expands or contracts, mechanically opening or closing the contacts. Such devices are typical for models released before the mid-2010s, and are often labeled TAM-133 or similar.
Electronic sensors, or thermistors, work by changing the resistance of a semiconductor material depending on heat. They have no moving mechanical parts and transmit data to the main control board in the form of an electrical signal. Refrigerators LG with a system No Frost usually have several such sensors installed: one in the refrigerator compartment, one in the freezer, and often a separate evaporator defrost sensor. Their sizes are minimal, and their location can be hidden behind plastic panels.
Visually distinguishing these elements is not difficult if you know what to look for. A mechanical thermostat is a large block with levers and a long copper or aluminum tube, which is braided along the contour of the chamber. An electronic thermistor is a small “tablet” or cylinder with a diameter of about 6 mm with two thin wires, often embedded in a plastic tip. Accuracy Electronic systems are much higher, which makes it possible to maintain the temperature with an error of less than one degree.
Why mechanical thermostats fail fail more often?
Mechanical wear of the contacts and fatigue of the bellows metal lead to the contacts sticking or no longer closing. In addition, the sensitive tube may receive a microcrack during installation, which will lead to leakage of the working gas and a complete loss of functionality of the device.
Localization of the thermostat in models with mechanical control
If your refrigerator LG belongs to the class of devices with mechanical control, you should look for the thermostat inside the refrigerator compartment. Most often it is located in the upper right or left corner, next to the lighting lamp or temperature control knob. Access to it does not always require complete disassembly; Sometimes it is enough to remove the plastic handle cover. However, in some models, such as series GA-409 or GC-069, the thermostat can be hidden behind the top decorative panel.
The sensitive tube of the mechanical thermostat runs along the perimeter of the inner wall of the refrigerator compartment. It is fixed in a special groove and covered with a plastic cover. It is important not to damage this tube during dismantling, since even minimal deformation can break the tightness of the system. The thermostat unit itself is usually attached to two screws or plastic latches to a metal case or internal partition.
To remove the mechanical regulator, it is often necessary to remove the top cover of the refrigerator completely. This is done by unscrewing the screws at the end and carefully snapping off the plastic clips. After removing the cover, access to the upper part of the inner chamber opens, where the thermostat is fixed. When reassembling, it is critically important to correctly place the sensitive tube in its original place, otherwise temperature control it will be incorrect.
☑️ Removing the mechanical thermostat
Location of sensors in refrigerators with the No Frost system
In refrigerators LGequipped with a system No Frost, the situation with searching for sensors is complicated by the presence of many sensors. There is no single “thermostat” in the classical sense. Instead, a network of thermistors is used, each of which is responsible for its own section. The main refrigerator compartment sensor is most often located in the air duct through which cold air is supplied from the freezer, or directly on the rear wall of the chamber.
The freezer compartment sensor is usually built into the evaporator or mounted on its aluminum radiator. In models with a linear compressor, access to it may be difficult due to the presence of additional thermal insulation. Often, to replace such a sensor, it is necessary to defrost the unit for at least 12 hours in order to get to the internal elements without the risk of damaging the fragile plastic fasteners in the cold.
The defrost sensor deserves special attention. It is located directly on the evaporator heater or built into it. In refrigerators LG this element is often integrated into the overall evaporator unit, and replacing it may require disassembling the entire back wall of the freezer. An error in installing this sensor will result in the system not understanding when to stop heating, which can result in overheating of the plastic or, conversely, ice accumulation.
| Sensor type | Location | Function | Resistance (at 25°C) |
|---|---|---|---|
| Refrigerator compartment sensor | Air duct or rear wall | Control temperature in the compartment | ~5-6 kOhm |
| Freezer chamber sensor | Evaporator or wall | Freeze control | ~5-6 kOhm |
| Defrost sensor | Stop defrosting | ~5-6 kOhm | |
| Condenser sensor | Overheat protection | ~10 kOhm |
Access to sensors through the control panel
In some modern models LG with a display on the door, the main control unit and some of the sensors can be integrated into the door structure. Although the thermistors themselves are located in chambers, the wires from them often go to a circuit board located at the top of the door or in a special box on top of the unit. Troubleshooting in such cases begins with checking the integrity of the cables running from the door hinges to the main body.
If the refrigerator shows an error associated with the sensor (for example, an error code, a flashing indicator), diagnostics are often carried out through the control panel. Entering the service menu allows you to see the current readings of all thermistors in real time. To enter the service mode, different combinations of buttons are used on different models, for example, simultaneously pressing the “Refrigerator” and “Ice” buttons for 3-5 seconds.
Access to the control board, which processes thermostat signals, is achieved by removing the top cover or the top part of the door. In models with an external display, the panel can be glued with double-sided tape and latches. Careful opening allows you to check whether signals from the sensors are reaching the board. If traces of oxidation or burnt tracks are visible on the board, the problem may not be in the sensor itself, but in its connection circuit.
⚠️ Attention: The characteristics of thermistors (resistance) may vary depending on the specific model and year of production. Always check the parameters of the new sensor with the markings of the old one or technical documentation.
Typical signs of malfunction of the thermostat and sensors
You can understand that the thermostat or temperature sensor in the refrigerator LG has failed by a number of indirect signs. The most obvious is the continuous operation of the compressor without switching off. If the unit hums for days, and the temperature inside drops below normal (food freezes in the refrigerator), this is a sure sign that mechanical thermostat is stuck in the "on" position or the sensor is transmitting false data about high temperature.
The opposite situation is The refrigerator is silent and does not start. The internal temperature rises, the food spoils, but the motor does not respond. This may mean that the thermostat contacts have oxidized and are not closing, or the electronic sensor indicates to the board that the temperature is already low enough that startup is not required. In such cases, lightly tapping the regulator handle or housing often helps, which can temporarily restore contact.
The third option is incorrect operation of the defrosting system. If the evaporator is covered with a “coat” of ice and the defrost sensor is faulty, the refrigerator will operate jerkily. The ice will block the air ducts, and the cold will stop flowing into the refrigerator compartment, although it will be frosty in the freezer. Diagnostics in this case requires a visual inspection of the evaporator after defrosting.
- ❄️ Food in the refrigerator compartment freezes, although the knob is set to minimum.
- 🔊 The compressor works without stopping or does not turn on at all.
- 💧 On the floor water appears under the refrigerator due to frequent defrost cycles.
- 💡 The indicators on the panel blink or show error codes.
Instructions for diagnostics and performance testing
To accurately diagnose a mechanical thermostat, it must be removed from the refrigerator. After disconnecting the wires, you can close them directly. If the compressor starts when it closes, then the problem is in the thermostat. To test sensitivity, you can immerse the end of the thermostat tube in a container of water at room temperature, and then cool it. The contacts should click when a certain temperature is reached, which can be recorded with a multimeter in dial mode.
Electronic sensors are checked by measuring their resistance using a multimeter. The values must correspond to the temperature curve declared by the manufacturer. Typically at room temperature (20-25°C) the resistance is about 5-10 kOhm. When heating with a hairdryer or cooling with a spray, the resistance should change smoothly. If the device shows an open circuit (infinity) or a short circuit (zero), the sensor is faulty needs to be replaced.
It is also important to check the integrity of the wires going to the sensor. In refrigerators LG there is often a broken wire at the point where it exits the sensor housing or in the area of the door hinge. Testing the circuit from the board connector to the sensor itself helps to eliminate wire breaks. Sometimes the problem is solved by simply cleaning the contacts in the connector, which may have oxidized due to moisture.
How to check a mechanical thermostat without a multimeter?
If there are no measuring instruments at hand, you can use the exclusion method. Close the two wires that went to the thermostat directly (after unplugging the refrigerator from the network!). Turn on the unit. If the compressor starts working and the refrigerator starts to freeze, the thermostat is faulty. Do not leave the refrigerator working with closed wires for a long time, as it will freeze indefinitely until you break the circuit.
Is it possible to use a thermostat from another refrigerator?
You can use an analogue only if the parameters match: on/off temperature range, length and diameter of the sensitive tube, as well as the location of the contacts. Installing the wrong thermostat will result in incorrect operation: either food will spoil or freeze. For electronic sensors, replacement is only possible with an original or a complete analogue with identical resistance.
Why does the refrigerator not turn off after replacing the thermostat?
Possible reasons: the adjustment screw (if any) is incorrectly adjusted, the sensitive tube does not fit well to the chamber wall, or a thermostat with an inappropriate temperature range is installed. It is also worth checking whether freon has entered the system (if the tube was damaged during installation), although in thermostats the gas is inert and safe, functionality is lost.