How to check the thermostat of the Atlant refrigerator

The situation when the refrigerator Atlant stops turning off or, conversely, does not start the compressor, often confuses the owner. In most cases, the cause of the failure is the thermostat (thermostat), which is responsible for maintaining the set temperature inside the chambers. This small unit is the link between the temperature of the evaporator and the electrical circuit of the engine.

Before calling a technician or buying a new part, it is necessary to carry out proper diagnostics. An erroneous conclusion can lead to unnecessary expenses, while the problem could lie in oxidized contacts or incorrect adjustment of the regulator knob. Understanding the principle of operation will allow you to independently determine the malfunction with an accuracy of up to 90%.

In this guide we will analyze testing methods without dismantling and using measuring instruments. You'll learn how to differentiate between a broken thermostat and problems with the start relay or compressor. We will also consider the design features of different models Atlant, since the location and type of sensors may differ.

Principle of operation and signs of thermostat malfunction

The thermostat is an electromechanical or electronic sensor that responds to changes in temperature in the evaporator or the air environment of the chamber. Classic models Atlant with mechanical control use a bellows tube filled with refrigerant. When the gas expands or contracts inside the tube, electrical contacts close or open, starting or stopping the compressor.

If this mechanism fails, the refrigerator behaves inappropriately. For example, food in the main chamber may freeze into ice, or, conversely, quickly deteriorate due to insufficient cold. It is important to distinguish between symptoms, since similar signs may indicate a freon leak or problems with the door seal.

Main signs indicating the need to check the thermostat:

• ❄️ The compressor works non-stop, creating excess cold or freezing a “fur coat.”
• 🔇 The engine is silent, although it is warm in the chamber, and the light is on.
• 🌡️ The temperature inside the chamber does not correspond to the position of the regulator knob.
• ⚡ Frequent on and off cycles (short operating cycle).

It is worth noting that in two-compressor models Atlant a separate sensor is responsible for each camera. Therefore, if the freezer is working normally, and the refrigerator compartment is warm, the problem is localized precisely in the circuit of the upper chamber.

⚠️ Attention: If you hear clicks inside the case, but the compressor does not start, do not rush to blame the thermostat. First, rule out a breakdown of the starting relay or the motor itself, since the symptoms may be similar.

Visual diagnostics and testing without instruments

The easiest way to make an initial assessment is to observe the behavior of the equipment and externally examine the accessible elements. For mechanical thermostats located inside the chamber, a "freeze" test can often be performed. This method does not require disassembling the case and using a multimeter, which makes it accessible to any user.

The essence of the method is forced cooling of the sensitive element. If the thermostat is working properly, it should “feel” the cold and close the circuit (or open it, depending on the operating logic). However, this method only works if the compressor does not turn on at all.

Algorithm for checking the freezing method:

1. Defrost the refrigerator completely and unplug it for 2 hours.
2. Find the thermostat (usually a knob with numbers inside the chamber).
3. Carefully remove the handle and plastic casing to gain access to the sensor housing.
4. Remove the thermostat from its seat without disconnecting the wires.
5. Put the sensitive tube or sensor housing in the freezer for 15-20 minutes.
6. Ring the contacts or simply plug in the refrigerator (observing safety precautions).

If after exposure to frost there is no click and the circuit does not close (the compressor does not hum), then Thermostat is faulty it requires replacement. Electronic temperature sensors cannot be checked in this way - they can fail due to condensation or temperature changes.

⚠️ Attention: When removing the thermostat, do not apply excessive force to the capillary tube. It is very thin and easily damaged, which will lead to leakage of filler gas and final breakdown of the unit.

Instrumental check with a multimeter

The most accurate result is obtained by using multimeter (tester). This device allows you to check the integrity of the electrical circuit and the presence of contact between the thermostat terminals. To carry out the work, you will need to remove the back cover of the refrigerator or dismantle the internal panel to gain access to the contact group.

Before starting measurements, make sure that the refrigerator is disconnected from the power supply. Switch the multimeter to resistance (Ohm) or continuity measurement mode. Touch the probes to the input and output contacts of the thermostat. At room temperature, the contacts of a mechanical thermostat are usually closed, and the device should show zero or emit a beep.

For deeper diagnostics, you can use a “water bath”:

• 🧊 Place the thermostat sensing tube in a container with water and ice (temperature about 0°C).
• 🔥 Carefully heat the water (you can use a hairdryer, but carefully), simulating an increase in temperature.
• 👀 Monitor the multimeter readings at the moment when the temperature reaches the trigger threshold.
• 🔊 A click and a break in the circuit should occur when a certain temperature is reached (depending on the marking).

If the resistance tends to infinity when the contacts are closed or, conversely, the circuit does not break when heated, the part must be replaced. In electronic models Atlant it is not the short circuit that is checked, but the change in the resistance of the thermistor itself, which should change smoothly with temperature changes.

The table below will help you navigate the readings for various conditions:

*The resistance value of the electronic thermistor depends on the specific model and should be checked with technical documentation.

Features of testing in different Atlant models

Refrigerators Atlant are produced in a large number of modifications, and the design of thermostats in them may differ. In older single-compressor models (KShD, MKhM series), the thermostat is often located inside the fridge compartment behind a plastic panel or built into the adjustment knob.

Modern two-compressor models (XM series) use the No Frost electronic control system. Here the mechanical thermostat has been replaced air temperature sensor (thermistor). Checking such an element requires knowledge of its nominal resistance. Typically this value is about 5–10 kOhm at room temperature and increases with cooling.

For models with the system No Frost the location of the sensors in the air channel of the evaporator is typical. Getting to them is more difficult: partial disassembly of the back wall of the freezer is often required. An error during assembly can lead to disruption of air circulation.

There is also a difference in markings. Mechanical thermostats Atlant are often equipped with parts from manufacturers Tam, K59, K50. The numbers in the marking indicate the temperature range of operation. Installing a thermostat with an inappropriate range will lead to incorrect operation: either the refrigerator will turn on frequently or will not be able to reach the desired temperature.

Marking of thermostats

Thermostats K59 are usually used for the refrigerator compartment, and K50 for the freezer. Installing K59 instead of K50 in the freezer will lead to the fact that it will not be able to freeze food to the desired temperature, since the shutdown range of K59 is higher (about -10.-14°C), while K50 turns off at -18.-24°C.

Replacing the thermostat: step-by-step instructions

If diagnostics confirmed the malfunction, the only solution is to replace the unit. This process requires accuracy and minimal skills in working with tools. The main rule is safety. All work is carried out only with the refrigerator completely disconnected from the network.

First you need to remove the old thermostat. Remove the adjustment knob, unscrew the mounting screws and carefully remove the housing. Disconnect the wires, having first photographed the connection diagram so as not to mix up the contacts when installing a new part. The capillary tube (if any) must be released from the mounting clips on the evaporator.

Installation of the new thermostat is done in the reverse order:

1. Fix the sensitive tube in the same position as the old one.
2. Connect the wires according to the photo or color code taken earlier marking.
3. Put the thermostat housing in place and secure with screws.
4. Put on the adjustment knob and set it to the middle position.
5. Turn on the refrigerator and check the first cycle of operation.

After replacement, it is recommended to let the refrigerator run for a few hours without loading products. This will allow the system to enter operating mode and make sure that the temperature is set correctly. If the compressor turns off after reaching cold, the replacement was successful.

⚠️ Attention: Never cut or extend the capillary tube of a mechanical thermostat. Violation of the tightness of the filling system will lead to an instant loss of sensitivity and the inability of the regulator to operate.

Frequent errors and operating tips

Refrigerator owners Atlant often make typical mistakes when diagnosing, mistaking other faults for a thermostat failure. For example, if ice is frozen in the chamber, this may be a problem with the defrost sensor, and not the main thermostat. Blindly replacing all sensors in a row is an expensive and ineffective way. No Frost ice has frozen over, this may be a problem with the defrost sensor and not the main thermostat. Blindly replacing all sensors in a row is an expensive and ineffective way.

Another common mistake is incorrect installation of the regulator knob. Users often turn the knob all the way to maximum, expecting rapid cooling. This leads to constant operation of the compressor and freezing of the evaporator, which is mistakenly taken for a “glitch” of the thermostat.

Basic recommendations for extending the life of the thermoregulation system:

• 🚫 Do not set the regulator to the maximum value unless necessary.
• 🧊 Make sure that the products did not touch the back wall of the chamber where the sensor is located.
• 🧹 Defrost the refrigerator regularly (if there is no No Frost) so that the layer of ice does not insulate the sensor.
• 🔌 In case of voltage surges, use a stabilizer, since the electronics of thermostats are sensitive to changes.

Remember that Even a working thermostat may not work correctly if the air circulation in the chamber is disrupted. Clogged ventilation holes or too dense loading of products distort the temperature readings, causing the system to operate in emergency mode.

Questions and answers (FAQ)

Is it possible to temporarily short-circuit the thermostat to make the refrigerator work?

Technically, you can connect the wires directly and the compressor will work. However, in this case, the refrigerator will work continuously until you unplug it. This will lead to severe freezing of food, breakdown of the compressor due to overheating and huge energy consumption. Use this method only for short-term defrosting or diagnostics.

Why does the refrigerator not turn off after replacing the thermostat?

There may be several reasons: a thermostat is installed with the wrong temperature range, the length of the capillary tube is incorrectly adjusted (it is not immersed enough in the cooling zone) or there is a freon leak in the system, which is why the temperature does not reach the threshold shutdown.

Where is the thermostat located in the Atlant No Frost refrigerator?

In models with the No Frost system, there is usually no mechanical thermostat with a tube. Its function is performed by an electronic sensor (thermistor), which is often built into a plastic casing on the inner wall of the freezer or hidden behind a decorative panel. To gain access, you often need to remove the back wall of the freezer.

How to understand that it is the thermostat that has failed, and not the relay?

If, when the thermostat contacts are closed directly (bypassing it), the compressor starts and works normally, it means that the motor and relay are working, and the problem is in the thermostat. If, when connected directly, the compressor hums, but does not start, or is silent, the problem is in the start relay, motor or wiring.