Sudden shutdown of the compressor or, conversely, its continuous operation without stopping are sure signs that a failure has occurred in the temperature control system. Often equipment owners Atlant face a situation where the unit stops freezing, although the motor is humming, or an ice coat forms inside the chamber when the fan is running. In most cases, the culprit of such anomalies is thermal relay, which is also called a thermostat or temperature sensor.
Diagnostics of this element does not always require calling a technician, since checking the thermostat on the refrigerator Atlant You can do it yourself, having a minimum set of tools and basic knowledge of electrical engineering. Understanding the operating principle of this unit will allow you to save time and money, as well as accurately determine whether a part needs to be replaced or the problem lies elsewhere in the electrical circuit.
Before starting disassembly, it is important to make sure that the refrigerator is disconnected from the network, since working with live electrical components is strictly prohibited. Next, we will consider in detail where to look for the sensor, what tools will be needed and how to interpret the obtained measurement results.
The principle of operation and the role of a thermal relay in the system
A thermal relay, or thermostat, is an electromechanical device that serves as the main temperature regulator in the refrigeration chamber. Its main task is to open and close the electrical power supply circuit of the compressor depending on the temperature inside the chamber. When the temperature rises above the set threshold, the contacts close, starting the motor, and when the specified minimum is reached, they open, stopping the cooling.
In refrigerators Atlant capillary thermostats are most often used, where the sensitive element is a long tube filled with gas or liquid. This tube, called capillary, reacts to the expansion or contraction of the working fluid when the temperature changes, mechanically acting on a group of contacts. Violation of the tightness of this system or sticking of contacts leads to incorrect operation of the entire unit.
⚠️ Attention: In modern models with electronic control, instead of a mechanical thermostat, a thermal sensor (thermistor) can be used. which transmits data to the control board. The principle of checking them is different: instead of checking the contacts, the change in resistance is measured depending on the temperature.
The malfunction of this unit can manifest itself in different ways: from a complete failure to start the compressor to its operation in non-stop mode, which leads to freezing of food and excessive energy consumption. Understanding exactly how it works thermostathelps to quickly diagnose the problem and distinguish it from a breakdown of the compressor itself or the start relay.
Typical signs of a thermal relay malfunction
You can determine that the problem lies in the thermostat according to a number of characteristic symptoms that appear during operation of the refrigerator Atlant. If you notice that the equipment behaves inconsistently with the established settings, you should take a closer look at the operation of the temperature control system.
The most obvious sign is the situation when the compressor does not turn on at all, although the power indicator is on and a hum is heard trying to start the engine. In this case, the power circuit is broken and the thermostat does not send a signal to start, even if the chamber is warm. The opposite situation is that the compressor works without interruption, without turning off even when the food has already turned into ice, which indicates that the contacts are stuck in the closed position.
- 🧊 It is too warm in the refrigerator compartment, the food spoils, and the motor is silent or turns on extremely rarely.
- ❄️ A thick layer of ice forms on the walls of the chamber crust, and the motor hums continuously, without going to rest.
- 🔌 When you turn the temperature control knob, you cannot hear the characteristic click that should be heard when the contacts are closed or opened.
It is also worth paying attention to the condition of the products: if the vegetables in the fruit drawer begin to freeze, and snow has formed in the freezer, this is a sure sign that which thermostat does not give a command to stop the engine. Ignoring these symptoms can lead to failure of the compressor itself due to overheating or water hammer with liquid refrigerant.
Tools and preparation for diagnostics
To carry out high-quality diagnostics, you will need a minimum set of tools that most home craftsmen can find. The main device will be multimeter (tester), capable of measuring resistance and testing circuits for integrity. Without this device, an accurate check of the thermal relay is impossible, since visual inspection rarely gives reliable results.
In addition to the multimeter, prepare screwdrivers (Phillips and flathead) for removing casings and control panels. Some models Atlant may require a knife or flat spatula to carefully pry up the plastic latches without damaging them. It would also be a good idea to use a cold source (for example, an ice pack or a can of compressed air turned upside down) to check the sensor’s response to cooling.
☑️ Preparing for diagnostics
It is important to ensure good lighting of the work area, since wires and contacts are often located in hard-to-reach places behind panels. Before starting work, be sure to defrost the chamber if there is a lot of ice in it, so that water does not get on the electrical contacts during disassembly.
Access to the thermal relay: disassembling the unit
The location of the thermal relay depends on the model of your refrigerator Atlant. In classic two-compartment models with mechanical control, the thermostat is usually located inside the refrigerator compartment, in the upper right corner, under a plastic trim or directly in the lighting control unit. In models with the system No Frost access may be limited to the rear panel.
First, remove the temperature control knob by pulling it towards you. Then carefully remove the plastic trim, which may be held in place by latches or screws. Under it you will see the thermostat housing with capillary tube coming out of it and several wires connected to the terminals. Be careful not to damage the fragile tube, as its deformation will lead to leakage of the working gas and the impossibility of further operation of the sensor.
⚠️ Attention: The capillary tube is very thin and sensitive. Do not bend it at an acute angle and do not pull it with force, otherwise the tightness of the system will be broken, and the thermostat will have to be changed in any case, even if the electrical part is working.
After gaining access to the contacts, disconnect the wires from the thermostat terminals. It is recommended to first take a photograph of the connection diagram or sketch it, so as not to mix up the wires during assembly, which can lead to a short circuit. Usually the wires are marked with colors or numbers corresponding to the diagram on the case.
Methods for checking a thermal relay with a multimeter
The most reliable way to check is to use a multimeter in resistance (Ohm) measurement mode or continuity testing. First, visually inspect the contacts: there should be no oxides, carbon deposits or traces of melting on them. If the contacts look normal, switch the multimeter to continuity mode.
At room temperature, the thermostat contacts should be closed (if it is not a specific shutdown sensor). Place the multimeter probes on the input and output pins. If the device beeps or shows resistance close to zero, the circuit is shorted. This is a normal condition for starting the compressor when the chamber is warm.
What to do if the multimeter shows infinity?
If at room temperature the multimeter shows an open circuit (one on the screen or no sound), this means that the contacts are not closing. Try gently tapping the thermostat body with the handle of a screwdriver - sometimes the contacts just stick. If this does not help, the element is faulty and requires replacement.
Next, you need to check the reaction of the thermostat to cold. To do this, connect the multimeter probes to the contacts and place the sensitive capillary tube (or the entire unit, if the design allows) in the freezer or apply ice to it. After 10-15 minutes, when the temperature drops below the response threshold, a click should be heard and the multimeter should show an open circuit (infinity resistance). If the circuit does not break in the cold, the thermostat will not turn off the compressor, and the food will freeze.
Comparative table of thermostat states
For ease of diagnosis, the test results can be systematized. Below is a table that will help you interpret the instrument readings and the state of the contacts under various conditions.
| Condition | Temperature conditions | Multimeter readings | Action |
|---|---|---|---|
| Normal (warm) | Room temperature (+20°C) | Circuit closed (0 Ohm, squeak) | Good |
| Normal (cold) | Cooling below -5°C | Circuit broken (∞ Ohm, silence) | Good |
| Fault 1 | Room temperature | Circuit broken (∞ Ohm) | Replacement (no start) |
| Fault 2 | Strong cooling | Circuit closed (0 Ohm) | Replacement (no shutdown) |
Use this data as a reference when checking your device. Remember that in different models Atlant threshold operating temperatures may differ slightly, but the principle of opening the circuit in the cold remains unchanged for most mechanical thermostats.
Frequent errors during diagnostics and replacement
When doing their own repairs, beginners often make mistakes that can lead to false conclusions or damage to serviceable components. One of the most common mistakes is checking the thermal relay without disconnecting the refrigerator from the network or without removing it from the case, which creates a risk of electric shock or short circuit.
Another mistake is to ignore the condition capillary tube. Even if the electrical contacts ring perfectly, a leak in the tube renders the thermostat useless. The gas evaporates and the pressure stops acting on the membrane, so the contacts do not open or close in time. Always check the tube for kinks, cracks or signs of corrosion.
- 🚫 Trying to clean the contacts with sandpaper is a temporary measure that will quickly lead to complete failure, as the silver coating is broken.
- 🚫 Using electrical tape to fix the capillary tube in the wrong position, which distorts the temperature readings.
- 🚫 Installing a thermostat with other temperature parameters (for example, instead of -18°C they set -12°C), which disrupts the operating mode of the refrigerator.
⚠️ Attention: Technical characteristics of thermostats (temperature on/off) may vary even within the same line of refrigerators. When replacing, always check the markings of the new part with the original so as not to disturb the temperature conditions of food storage.
Also, do not forget that in some complex models with electronics, diagnostics may require checking not only the sensor itself, but also the wires going to the control board. A break in the wiring will give the same symptoms as a malfunction of the relay itself.
Replacing the thermal relay: a brief algorithm
If diagnostics showed that the thermal relay is faulty, it must be replaced. The replacement process in refrigerators Atlant usually does not take much time. First, purchase a similar part with identical markings. Then dismantle the old thermostat by carefully pulling the capillary tube out of the mounting hole.
Install the new sensor, securing the tube in the same position as the old one. Connect the wires according to the diagram or photograph you made earlier. Make sure all connections are secure and insulated. After assembly, turn on the refrigerator and monitor its operation for several hours, checking the on and off cycles.
A correct replacement will restore the normal operation of your refrigerator Atlant and extend the service life of products. If after replacement the problem does not disappear, perhaps the fault lies in the start relay, compressor or defrost system, which will require more in-depth professional diagnostics.
Is it possible to temporarily short-circuit the thermal relay to make the refrigerator work?
Technically, you can short-circuit the contacts and the compressor will start, but doing this is strictly not recommended for long-term use. The refrigerator will run continuously until you turn it off manually, which will lead to food freezing, evaporator icing, and possible compressor failure due to overload. This is only permissible as a short-term measure to defrost or check the compressor.
Where is the thermostat located in the Atlant refrigerator with the No Frost system?
In models No Frost thermal sensors (often there are several of them) can be located inside the air duct, on the back wall of the chamber or in the evaporator area. Access to them is usually difficult and requires removing the back panel inside the chamber or even dismantling the entire internal box, since they are built into the air circulation system.
Why does the new thermostat click more often than the old one?
The frequency of clicks depends on the hysteresis (difference between on and off temperatures) of a particular instance of the sensor. New thermostats may have more accurate or slightly different factory settings. If the difference is not critical and the temperature in the chamber remains normal, this is not a defect. However, turning on too frequently (every 2-3 minutes) may indicate a malfunction or a freon leak.
Which multimeter is best to use for testing?
Any entry-level digital multimeter capable of measuring resistance in the range from 0 to 2000 Ohms and having a dialing mode with an audible signal is suitable for household diagnostics. Professional accuracy is not required here, the main thing is to clearly see the presence or absence of contact.