Sudden defrosting of food or, conversely, the formation of an ice block inside the chamber are sure signs that the temperature control system has failed. Most often, the culprit is the thermostat, which stops reading readings correctly and commanding the compressor to turn on or off. Replacing this unit on your own is quite possible for a person with basic skills in handling tools and an understanding of the basics of electrical safety.
Before proceeding with dismantling, you need to make sure that the problem lies in the thermostat, and not in a freon leak or a malfunction of the start relay. If the refrigerator runs continuously without turning off, or, on the contrary, is silent when plugged in, but the light is on, there is a high probability of failure of the thermostat. In this article we will analyze in detail the process of diagnostics, selection of an analogue and installation of a new temperature controller for various models of household appliances. You will learn how to properly remove the old sensor without damaging the capillary tube, and how to configure the new device for correct operation. A competent approach will extend the life of the refrigerator and save a significant amount on calling a technician. thermostat.
In this article we will analyze in detail the process of diagnostics, selection of an analogue and installation of a new temperature controller for various models of household appliances. You will learn how to properly remove the old sensor without damaging the capillary tube, and how to configure the new device for correct operation. A competent approach will extend the life of the refrigerator and save a significant amount on calling a technician.
The principle of operation and signs of a malfunction of the thermostat
The temperature regulator, or thermostat, is an electromechanical or electronic device that controls the temperature inside the refrigerator compartment. In classic models, it works based on a change in the volume of gas or liquid in a sealed capillary tube, which is attached to the evaporator. As the tube cools, the gas compresses and the contacts open, turning off the compressor. When the temperature rises, the gas expands, completing the circuit and starting the engine.
Understanding this principle helps diagnose a breakdown. If you observe that the refrigerator is “threshing” without stopping, forming a snow coat on the walls, this means that the thermostat contacts are “stuck” in the closed state. The compressor is working hard, trying to achieve non-existent cold. In the opposite situation, when the unit is silent and warm inside, the contacts simply do not close, and the system “thinks” that the cold has already been reached.
⚠️ Attention: If you hear a characteristic click when you try to start the compressor, but it immediately stalls, the problem may not be in the thermostat, but in the starting relay or the motor itself. Do not rush to change parts at random.
Electronic thermostats, often found in models with a system No Frost and display, work differently. There, the temperature is measured by thermistors (resistors that change resistance when heated). Their breakdown is often accompanied by error codes on the display, but sometimes the refrigerator simply stops responding to commands from the control panel. In such cases, replacement requires a more in-depth diagnosis of the control board.
The main symptoms of a faulty mechanical thermostat include:
- ❄️ The compressor runs non-stop or does not turn on at all.
- 🧊 It is too cold in the refrigerator compartment or, conversely, food begins to spoil.
- 💡 The light is constantly on, even when the door is closed (if the contacts are stuck).
- 🔌 Traces of oxidation, burning or melting of the plastic are visible on the thermostat body.
Diagnostics and preparation for replacement
Before purchasing a new part, it is necessary to conduct an initial diagnosis to rule out others reasons. The simplest method is “freezing”. If the refrigerator does not turn on, you can remove the thermostat, place it in the freezer for 30-40 minutes (after disconnecting the wires), and then “ring” the contacts with a tester. If resistance does not appear, the part is definitely faulty.
To replace it, you will need a minimum set of tools. It is important to prepare a workplace with good lighting, since the insides of the refrigerator are often hidden in hard-to-reach niches. Don't forget about the multimeter - without it it will be impossible to check the circuit and the new device. You may also need a flathead and Phillips screwdriver, and in some cases, pliers.
A critically important step is selecting the correct analogue. Thermostats are marked differently (K-50, K-59, TAM-112, TAM-133, etc.). The numbers and letters in the marking indicate the length capillary tube, on/off temperature range and mounting method. Installing an unsuitable regulator will lead to incorrect operation: for example, the refrigerator will turn off at +5°C, which is not enough to store food.
Comparison table of popular thermostat models:
| Model | Type refrigerator | Tube length | Features |
|---|---|---|---|
| K-59 | Single chamber | 0.73 m | Standard for many models |
| K-50 | Double-chamber | 0.73 m | For chambers with a weeping evaporator |
| TAM-133 | Single-chamber | 1.3 m | Analogue K-59, long tube |
| TAM-112 | Two-chamber | 0.73 m | Analogue K-50, compact |
Is it possible to use a thermostat with a longer tube?
Yes, you can. The excess length of the capillary tube is carefully rolled into a ring and placed inside the housing, being careful not to bend it. The main thing is that the tube does not dangle or touch moving parts.
Removing the old thermostat
The process of removing the old regulator depends on the design of your refrigerator. On top-freezer models, the thermostat is often located inside the refrigerator compartment, under a plastic panel or behind a light bulb. In two-chamber units with a bottom freezer, access can be through the rear wall from the outside or by removing the top cover.
First, always remove the plastic temperature control knob. It is usually simply pulled together by hand or held on with one screw under a decorative plug. After this, access to the mounting screws of the thermostat housing itself opens. Carefully unscrew them, trying not to drop them inside the cabinet.
The most crucial moment is removing capillary tube from the evaporator. It is secured in a special hole and can be glued or clamped with a plastic holder. Do not pull the tube itself with force - it will (very easily) bend or burst. Proceed carefully, loosening the base and gradually pulling out the sensor.
☑️ Tools for dismantling
When the tube is free, disconnect the electrical wires. Before doing this, it is strongly recommended to photograph the connection diagram or mark the wires with a marker so that when installing a new device you do not mix up the contacts. There are usually three of them: one for the compressor, one for the light bulb/fan and a general one. After disconnecting the wires, the old thermostat can be completely removed from the refrigerator.
Installation and connection of a new sensor
Installation of a new thermostat is carried out in the reverse order of dismantling. First, you need to carefully insert the capillary tube into the mounting hole of the evaporator. The immersion depth should be the same as that of the old sensor (usually 10-14 cm, but it is better to be guided by the marks or the length of the removed part). If the tube of the new thermostat is longer, its excess is carefully rolled up and fixed inside the housing.
Connecting the electrical part requires care. Use previously taken photographs or markings. On mechanical thermostats, the contacts are often identified by numbers (3, 4, 6) or wire colors. It is important to ensure tight contact so that sparking does not occur at the connection point, which can lead to burning of the terminals.
After connecting the wires, secure the thermostat housing with screws and install the regulator knob in place. Make sure that the handle rotates freely and does not touch adjacent elements. Only after complete assembly can you proceed to test activation.
Checking the functionality begins by plugging in the refrigerator. During the first hour of operation, listen for sounds: the compressor should start, run for a certain time and turn off. If the refrigerator is turned off, but it is still warm inside, it may need adjustment.
Setting and adjusting the temperature mode
After replacing the thermostat, its initial adjustment is often required. Factory settings may not match your specific camera's requirements. The adjustment is made using a special screw located on the thermostat body (often it is hidden under a seal or plug) or by selecting the position of the handle.
Rotating the adjustment screw clockwise usually increases the shutdown temperature (the refrigerator will turn off at higher values), and counterclockwise - lowers it. Be careful: one full turn of the screw can change the temperature by several degrees. Make adjustments in small steps (1/4 or 1/2 turn) and wait for the cycle to stabilize.
For precise adjustments, it is better to use an external thermometer placed in a glass of water in the center of the chamber. This will give an objective picture, since built-in sensors can lie. The optimal temperature in the refrigerator compartment should be from +2°C to +6°C.
If, after replacement and adjustment, the operating cycle is not normal (for example, the refrigerator turns off for 1 minute and turns on again), the thermostat may have been selected with an inappropriate temperature range or the capillary pipe is too short. In this case, you will need to replace it again with a more suitable model.
Frequent errors and safety measures
The most common mistake during self-repair is damage to the capillary tube. If you hear a hissing sound or smell gas, it means the seal is broken. Trying to solder the tube yourself at home is impossibleas the system requires evacuation and charging with freon. In this case, you will have to call a technician for refilling.
Another mistake is ignoring grounding. If your refrigerator is old and does not have a Euro plug, and the apartment has a three-wire network, make sure that the case is grounded. Poor contact in the thermostat can lead to voltage on the body, which is life-threatening.
Also, do not use “bugs” or twists to connect the wires. All connections must be made using terminal blocks or high-quality soldering with heat shrink insulation. Poor contact will lead to heating and possible fire of the plastic inside the refrigerator.
⚠️ Attention: Never check the operation of the thermostat by closing the contacts with your fingers or live metal objects! This can lead to electric shock or short circuit.
If you are not confident in your abilities or are afraid of damaging complex components, it is better to entrust the work to professionals. However, if you acted carefully and followed the instructions, replacing the thermostat is a great way to revive the refrigerator at minimal cost.
What to do if the new thermostat clicks, but the compressor does not start?
Check the start relay and the compressor itself. Perhaps the problem was complex, and while the old thermostat was working, it simply did not give a start command due to its malfunction, hiding the motor problem.
Questions and answers (FAQ)
Is it possible to temporarily short-circuit the thermostat to make the refrigerator work?
Yes, you can connect the wires going to compressor, bypassing the thermostat. The refrigerator will run continuously until it reaches the lowest possible temperature. This is an emergency measure to preserve food before purchasing spare parts, but you cannot operate the equipment like this for a long time - the compressor will burn out.
What is the difference between the K-59 thermostat and the K-50?
The main difference is in the temperature range. K-59 (typically for single chambers) turns off the compressor at lower temperatures than K-50 (for double chambers). If you put the K-59 in a two-chamber refrigerator, the main chamber will be too cold and the food will freeze.
Why does the refrigerator not turn off for a long time after replacing the thermostat?
This may be due to the fact that the capillary tube is not immersed deep enough in the evaporator, or the new thermostat requires adjustment. Also check the tightness of the door and the condition of the seal - if warm air gets inside, the operating cycle will be longer.
Where is the thermostat located in Indesit and Ariston refrigerators?
In most models of these brands, the thermostat is located inside the refrigerator compartment, in the upper right corner, under the plastic cover, where the light bulb is also located. You can get to it by removing this cover.