Sudden spoilage of food or, conversely, the formation of an ice block in the refrigerator compartment are sure signs that thermostat has failed. This small device is responsible for maintaining a stable temperature regime by opening and closing the electrical circuit of the compressor at the right time. If you notice that the refrigerator has stopped turning off or is working too rarely, the problem most likely lies in the temperature sensor.
Replacing this element does not always require calling a technician, since in many models the dismantling procedure is quite simple and does not require special tools. However, it is important to understand that thermostats there are different types, and setting them up requires care. In this article, we will look at how to independently diagnose a breakdown and safely make a replacement, returning your Indesit, Atlant or Beko normal operation.
Before starting disassembly, make sure that you have completely disconnected the equipment from the power supply. Working with electrical components requires basic safety precautions. It is also worth preparing a place to work where all the parts will be at hand, and the risk of losing small screws is minimized.
Principle of operation and signs of a malfunction of the thermostat
The main task of the thermostat is to control the temperature inside the chambers and control the start of the engine. Inside the device there is a sensitive capillary tubefilled with refrigerant, which reacts to changes in heat. When heated, the gas expands, the pressure rises, and the contacts open, stopping the compressor. When cooling, the process occurs in the reverse order.
You can understand that the device has failed by characteristic symptoms that are difficult to ignore. Most often, users are faced with the fact that the refrigerator hums non-stop, trying to achieve non-existent cold, or remains silent for days, allowing food to defrost. In some cases, the unit may turn on and off too often, which also indicates a failure in the control system.
⚠️ Attention: If the compressor operates continuously for more than 24 hours, this can lead to its overheating and failure, which will require much more expensive repairs than simply replacing the sensor.
Indirect signs include the appearance of condensation on external the walls of the case or the formation of a “fur coat” in the freezer, even if the operating mode has not changed. Sometimes the thermostat simply “sticks” in one position, and turning the adjustment knob does not give any result - the motor does not respond to your actions.
Diagnostics: checking the thermostat before replacing
Before buying a new part, you need to make sure that the problem is in it, and not in a freon leak or a malfunction of the start relay. The simplest and most accessible testing method is visual inspection and testing with a multimeter. To do this, you will need to remove the thermostat and ring its contacts in different temperature conditions.
First, remove the device from the case and lower its sensitive tube into a container with cold water (about 0 degrees) for a few minutes. Then check the resistance between the contacts. If the thermostat is working properly, the multimeter should show the presence of a circuit (or its break, depending on the type of contacts) when cooling and change readings when warming up in your hands.
It is also worth paying attention to the condition of the capillary tube itself. If traces of corrosion, creases or damage to the insulation are visible on it, the seal is broken and the gas has escaped. In this case, restoration is impossible, only complete replacement of the unit to a new one is required.
Necessary tools and preparation for work
For successful repairs, you do not need complex professional tools. A basic DIY kit, which many people have, is enough. The main thing is to have working diagnostic devices on hand so as not to do unnecessary work.
Here is a list of what is needed for replacement:
- 🔧 Screwdrivers (phillips and flat) for removing panels and dismantling fasteners.
- 🔌 Multimeter for checking the electrical circuit and integrity contacts.
- 🧊 A container with water and ice for testing the sensitivity of the thermostat.
- 🔦 A flashlight for better illumination of the interior of the refrigerator compartment.
It is important to select an analogue of the failed part in advance. Thermostats may differ in the length of the capillary tube, the type of contacts and the method of fastening. Find the markings on the body of the old appliance (usually a code like TAM-133 or K-59) and look for a replacement using these parameters.
☑️ Preparation for repair
Step-by-step instructions: dismantling the old thermostat
The process of removing the thermostat may be slightly vary depending on the refrigerator model, but the general algorithm of actions remains the same. In most modern models, such as Samsung or LG, the sensor is hidden behind a plastic panel inside the refrigerator compartment.
First you need to clear access to the assembly. To do this, remove all shelves that interfere with work and dismantle the lampshade if it blocks access to the screws. Often the thermostat is mounted on a common bar along with a defrost button and a light bulb. Carefully unscrew the mounting screws and remove the plastic casing.
⚠️ Attention: The plastic in older refrigerators can be brittle. Be careful not to break the latches or the panel itself when dismantling.
After removing the casing, you will see the thermostat itself and the long tube coming from it. Record the position of the tube (you can take a photo), then disconnect the electrical wires, remembering or marking their location. The tube is usually simply pulled out of the hole in the chamber wall, but sometimes it is secured with a bracket that needs to be bent.
Installation of a new thermostat and connection diagram
Installation of a new device is carried out in the reverse order of dismantling. The most important thing is to lay the capillary tube correctly. It must be located in the same place and have the same configuration as the old one, otherwise the refrigerator will not read the temperature correctly.
Carefully insert the tube into the hole until it stops, being careful not to damage it with the sharp edges of the plastic. Then connect the wires to the pins. If you did not photograph the circuit, refer to the documentation for the new part or use the color coding of the wires (usually white, red and yellow/green).
Below is a table of typical contact designations for common models of thermostats:
| Contact type | Designation on diagram | Wire color (often) | Function |
|---|---|---|---|
| Network input | L or 3 | Red / Brown | Voltage supply |
| Output to compressor | 4 or 6 | Black / White | Starting the motor |
| Grounding | Ground | Yellow-green | Housing safety |
| Lamp/Fan | 2 or L | White / Orange | Add. circuits |
After connecting the wires, assemble the plastic casing and secure it with screws. Make sure that all the elements are in place and nothing is preventing the door from closing.
What to do if the tube is too long?
If the new capillary tube is longer than the old one, you can carefully roll it into a ring inside the refrigerator body (behind the back wall), but in no case bend it or cut it. Failure to seal the tube will lead to immediate failure of the new thermostat.
Setting up and checking operation after replacement
After assembly, do not rush to load products. Plug in the refrigerator and leave it idle for at least 2 hours. This is necessary for the unit to reach the desired temperature and turn off. If the compressor stops and turns on again after a while, you have completed the task.
Check the operation of the temperature regulator. Turning the knob should change the intervals at which the motor operates. If you turn the knob towards maximum cold, the compressor should run longer. In the minimum position - turn off more often.
If the refrigerator is working correctly, you can gradually load food. Monitor the condition of the evaporator during the first day: it should not be covered with a continuous layer of ice, but only with light frost.
Common mistakes during self-repair
Beginners often make mistakes that nullify all efforts. One of the most common is incorrect installation of the capillary tube. If it does not touch the evaporator wall or dangles in the air, the thermostat will “lie” and the temperature in the chamber will not stabilize.
Another mistake is ignoring grounding. When installing a new thermostat, many people forget to connect the ground wire, considering it unnecessary. This violates the electrical safety of the device and can lead to electric shock when touching the metal parts of the case.
⚠️ Attention: Technical characteristics of refrigerators may vary depending on the year of manufacture and the specific modification. Always check the connection diagram with the documentation included with your device or with the markings on the thermostat itself.
You should also avoid sudden movements when working with the tube. The metal from which it is made is soft and easily deformed. Any microcrack will lead to leakage of sensitive gas, and the device will stop responding to temperature changes.
Is it possible to use a thermostat from another refrigerator?
Theoretically, it is possible if the mounting dimensions and length of the tube are the same. However, the response temperature range may vary. For example, a thermostat from a single-chamber refrigerator may not be suitable for a two-chamber refrigerator, since they have different requirements for the shutdown temperature.
FAQ: Frequently asked questions
Is it possible to replace the thermostat with a universal analogue?
Yes, there are universal thermostats (for example, series TAM or K), which are suitable for many models. The main thing is that the length of the capillary tube and the type of contacts match. However, it is better to look for the original part number for your model Electrolux or Boschto ensure accuracy.
Why does the new thermostat click, but the refrigerator does not turn on?
This may indicate a malfunction of the compressor start relay or the motor itself. It is also possible that you have connected the wires to the thermostat terminals incorrectly. Check the connection diagram again and test the circuit with a multimeter.
How often should you change the thermostat?
The service life of a thermostat is usually 5-10 years, but it can fail even earlier due to power surges or mechanical damage. Scheduled replacement is not required; it is changed only when signs of malfunction appear.
Does the length of the capillary tube affect the operation?
Yes, the length of the tube is critically important. If it is too short, the sensing element will not reach the desired area of the evaporator. If it is too long, the tube will have to be rolled up, which may disrupt heat transfer. It is better to take an analogue with a length equal to or slightly longer than the original.