The situation when the refrigerator stops freezing or, conversely, turns food into ice, often indicates a malfunction thermostat. In two-chamber models of the Belarusian brand Atlant this unit is a key element of the control system, responsible for the cyclic operation of the compressor. If you notice that the unit works without interruptions or does not turn on at all, there is a high probability that the temperature sensor has failed and requires replacement.
Replacing the thermostat is a procedure that is accessible even to a beginner in repairing household appliances, if you act carefully and follow the sequence. Thermoregulator (or thermostat) is a mechanical or electronic device that reads the temperature in the evaporator or inside the chamber and opens the electrical circuit when the specified parameters are reached. Incorrect connection can lead to failure of the compressor or a violation of the temperature regime, so it is important to understand the principle of operation and the connection diagram.
In this article we will analyze in detail the process of diagnostics, selection of compatible spare parts and, most importantly, the correct connection of the thermostat to the electrical network of the refrigerator Atlant. We will look at the nuances of working with different types of sensors, including models with a defrost button, and will pay special attention to safety when working with high voltage.
Diagnostics and selection of a new thermostat
Before disassembling the refrigerator, you need to make sure that the problem lies in the thermostat. The main symptoms of a malfunction are the absence of a characteristic click when turning the adjustment knob or continuous operation of the compressor even at minimum settings. In some cases, thermostat may give false readings, causing the chamber to be too warm or too cold.
For accurate diagnostics, a multimeter is often used in dial mode. At room temperature, the contacts of a working mechanical thermostat should be closed (the circuit rings). If you take the sensor out into the cold (for example, put it in the freezer for 15-20 minutes) and the circuit does not break, the part is faulty. Electronic sensors, such as TAM-133 or imported analogues Rancoare checked by resistance, which should change with temperature changes.
When choosing a new spare part, it is critical to pay attention to the markings and length of the capillary tube. For refrigerators Atlant thermostats of the T-132, T-133 or TAM-133series are most often used. The length of the tube can vary from 0.6 to 1.3 meters, and if you buy one that is too long, you will have to carefully place it in the free space without bending it.
- 🔍 Check the markings on the body of the old sensor - it should match the new part or be a complete analogue.
- 🌡️ Make sure that the temperature range of the new thermostat meets the requirements of your refrigerator model.
- 🔌 Pay attention to number of contacts: for models with a quick freeze button, thermostats with three terminals are needed, not two.
⚠️ Attention: The capillary tube of the thermostat is filled with refrigerant and is very sensitive to mechanical damage. Do not bend the tube at an acute angle or hit it, otherwise the seal will be broken and the sensor will stop responding to temperature changes.
Preparation for replacement and safety precautions
Any work related to the electrical components of the refrigerator requires strict adherence to electrical safety rules. The first and most important step is to completely disconnect the unit from the power supply. It is not enough to simply turn off the button on the panel; you need to unplug the plug from the socket, since during dismantling you will touch live parts.
For a successful replacement you will need a minimum set of tools: Phillips and flat-head screwdrivers, side cutters (nippers), insulating tape or heat shrink, as well as a multimeter. Prepare a place to work in advance: the space around the refrigerator should be free, and the lighting should be sufficient to see the colors of the wires and terminal markings.
If your refrigerator Atlant has a two-chamber, access to the thermostat is usually located inside the refrigerator compartment (top right or left) or hidden behind a plastic panel at the top of the case. In models with the No Frost system, access may be complicated by the presence of additional covers. Before starting dismantling, it is recommended to photograph the original connection of the wires to avoid errors during assembly.
☑️ Preparing to replace the thermostat
- 🛠️ Prepare insulating materials in advance so as not to look for them while working under voltage.
- 📸 Take a photo of the connection before disassembly - this is your insurance against errors during assembly.
- 🧤 Use gloves to avoid leaving greasy marks on the inside of the refrigerator and protect your hands from sharp plastic edges.
Removing the old thermostat
The process of removing the old sensor begins with dismantling the adjustment knob temperature. In most models Atlant it is simply removed by hand, but in some cases it may be necessary to carefully pry it with a flat screwdriver through the technological hole. After removing the handle, access to the fastening screws of the thermostat housing opens.
After unscrewing the screws, you will see the thermostat block itself and the wires coming from it. Depending on the model, the wires can be connected through detachable terminals or twisted and insulated. If twists are used, they must be carefully separated, after making sure that the refrigerator is de-energized. The capillary tube that runs through the chamber wall to the evaporator must be released very carefully.
It is important to remember or mark with a marker which wire is connected where, especially if the color coding is not obvious or the wires have faded over time. In thermostats with a defrost button, the circuit is more complicated: there are three contacts, and they cannot be mixed up, otherwise the button will not work or the refrigerator will not start. The old sensor is removed from the mounting hole, and the capillary tube is carefully pulled out of the channel.
⚠️ Attention: When pulling the capillary tube out of the channel, do not use excessive force. If the tube is stuck, try gently turning it or slightly warming the outlet with a hairdryer to soften the seal, but do not overheat the plastic of the refrigerator body.
What to do if the terminals are oxidized?
If you find green deposits or rust on the contacts, be sure to clean them with fine sandpaper or a file before connecting a new one thermostat. Oxidation creates additional resistance, which can lead to heating of the contacts and repeated failure.
Connection diagram and installation of a new sensor
Installation of a new thermostat is carried out in the reverse order of dismantling. The capillary tube of the new sensor is inserted into the channel until it stops, being careful not to damage it. Then the thermostat block is fixed in the niche. The most critical step is the electrical connection. In standard two-contact thermostats (for example, T-132), the order of connecting phase and zero does not matter, since the contacts open the circuit.
Thermostats with a third contact for the quick freeze button are a completely different matter (for example, T-133, TAM-133). It is critical here not to confuse the contacts. Typically the circuit looks like this: one contact is the power input, the second is the output to the compressor, the third is the output to the defrost button. If you connect the wires incorrectly, the refrigerator will either not turn on or will only work in fast freezing mode, ignoring the shutdown button.
To connect the wires, it is best to use factory terminals or high-quality twisting followed by soldering and insulation heat shrink. Simple electrical tape can dry out over time due to cold and moisture, which will lead to a short circuit. After connecting all wires, make sure that they do not touch moving parts or hot elements (if we are talking about the rear of the unit).
| Thermostat type | Number of contacts | Availability of defrost button | Application in Atlant |
|---|---|---|---|
| T-132 | 2 | No | Single-chamber, simple two-chamber |
| T-133 | 3 | Yes | Two-chamber with fast freezing function |
| TAM-133 | 3 | Yes | T-133 analogue, often interchangeable |
| Ranco K59 | 2 or 3 | Depends on the modification | Imported analogues for modern models |
- ⚡ Use only copper wires for extension, if the length of the standard ones is not enough, and carefully insulate the connections.
- 🔧 Securely fasten the thermostat housing with screws so that vibration of the compressor does not loosen the contacts.
- 🧊 Make sure that the sensitive element (tube) fits tightly to the evaporator or is correctly located in the channel.
Setting up and testing operation
After all connections are made and the case is assembled, you can begin testing. Plug in the refrigerator and set the thermostat knob to the middle position (usually number 3 or 4). After a few seconds, a characteristic click should be heard and the compressor will start. If this does not happen, check for voltage at the thermostat input.
Let the refrigerator operate for about 30-40 minutes. During this time, the temperature in the chamber should begin to decrease. Try turning the adjustment knob counterclockwise to minimum. A working thermostat should turn off the compressor (click). If the compressor continues to hum even at the minimum setting, the thermostat may be faulty or its sensitive element is installed incorrectly.
Pay attention to the duration of the operating cycles. The normal mode is when the compressor runs for about 10-15 minutes and rests for 20-30 minutes (depending on the load and ambient temperature). If the operating cycle is too short (2-3 minutes), this may indicate that the thermostat is not selected correctly or its tube is in poor contact with the object being cooled.
⚠️ Attention: Technical characteristics of refrigerators may vary slightly depending on the year of manufacture and the specific modification. If you see that the wiring diagram differs from that described, check the electrical diagram pasted on the inside wall of the refrigerator or the manufacturer's instructions.
Frequent errors and ways to eliminate them
One of the most common errors is incorrect installation of the capillary tube. If it is not fully inserted into the channel or is not pressed against the evaporator, the thermostat will “lie”, reading the air temperature in the chamber, and not the temperature of the cooling element. This will lead to rare inclusions and damage to the products.
Another mistake is poor contact in the twists. Over time, the junction oxidizes, the resistance increases, sparking and heating occur. This can lead to insulation melting and even fire. Always use high-quality materials for insulation and, if possible, solder connections.
Some technicians try to adjust the factory settings of the thermostat by turning the screws under the seal. Doing this without special equipment and knowledge is strictly not recommended. You can reset the calibration and the refrigerator will not work correctly. If the new thermostat does not work correctly, it is easier to replace it with another one than to try to “tweak” this one.
Frequently asked questions (FAQ)
Is it possible to install a thermostat from another manufacturer, for example, Ranco or Danfoss?
Yes, it is possible, if the overall dimensions and capillary length are the same tubes and temperature range. Imported analogues are often even more reliable than domestic ones. The main thing is to connect the wires correctly, since the numbering of contacts may differ for different brands.
Why does the refrigerator not turn off after replacing the thermostat?
Possible reasons: the wires are incorrectly connected (especially in three-pin models), the capillary tube is not in contact with the evaporator, or the new thermostat itself is defective. It is also worth checking whether the quick freeze button is stuck.
Do you need to defrost the refrigerator before replacing the thermostat?
It is advisable. Although the thermostat is located in the upper part, when dismantling it, pieces of ice may fall out of the evaporator if the No Frost system is clogged. In addition, working with a warm refrigerator (after defrosting) is safer and more convenient for plastic elements.
How to understand that the thermostat is “lying” and shows the wrong temperature?
If the food in the refrigerator freezes when the knob is set to maximum heat, or, conversely, the milk turns sour at maximum cold load, most likely the thermostat needs to be replaced or adjustments (settings).