A malfunction of the temperature control system is one of the most common reasons why owners of household appliances contact service centers. If your Atlant two-chamber refrigerator stops freezing or, conversely, turns food into ice blocks, the thermostat is usually the first suspect. This small but critical component is responsible for turning the compressor on and off, maintaining a given microclimate inside the chambers.
Self-diagnosis allows you to save significant money and time, since in most cases replacing the thermostat does not require complex professional equipment. However, in order not to buy unnecessary parts, you need to make sure that this particular element is working, and not the compressor or start relay. In this article, we will analyze proven testing methods that will help you determine the condition of thermostat with high accuracy.
Before you begin disassembling the unit, it is important to understand the principle of operation of the unit. A thermostat is a mechanical or electronic device that closes an electrical circuit when the temperature rises and opens it when the set values are reached. Models Atlant most often use mechanical relays that are sensitive to changes in gas pressure inside the capillary tube. Understanding this physics of the process will help you correctly interpret the test results.
Main signs of a thermostat malfunction
The first step in diagnosis is a visual inspection and analysis of the behavior of the refrigerator. If the compressor hums continuously, without stopping for a minute, this is a sure sign that the circuit is not opening. In such a situation thermostat simply “does not see” that the required cold temperature has already been reached, and continues to supply voltage to the motor.
⚠️ Attention: Long-term operation of the compressor in non-stop mode can lead to overheating of the windings and failure of the motor itself, therefore If this symptom is detected, it is better to temporarily disconnect the device from the network.
The opposite situation, when the motor is silent and it is warm inside the chamber, may also indicate a breakdown. In this case, the contacts inside the relay could oxidize or become stuck in the open position, interrupting the flow of electricity. It is also worth paying attention to the following symptoms:
- 🧊 Food in the refrigerator compartment is defrosting, although the regulator is turned to minimum cold.
- ❄️ An excessive “fur coat” forms in the freezer compartment, and ice build-ups appear on the back wall of the main chamber.
- 🔌 The compressor makes a click when trying to start, but immediately stalls, after which it remains silent for a long time.
Sometimes users confuse a thermostat failure with a freon leak. To differentiate these problems, you need to listen to the operation of the unit. If the engine runs rough or only turns on for a very short time, the problem may not be with the sensor, but with the refrigerant. However, if the operating cycle is clearly broken (or does not stop or does not start), the focus shifts to control automation.
Preparation for diagnostics: tools and safety
To conduct a quality test, you will need a minimum set of tools that any home craftsman will have. The main device will be multimeter (tester), which allows you to measure resistance and test circuits for open circuits. Without this device, accurate diagnostics is impossible, since it is impossible to determine the integrity of the contacts inside the sealed case by eye.
Also prepare a flat-head and Phillips screwdriver for removing protective panels and plastic casings. Some models Atlant may require pliers to carefully remove the terminals. Before starting any work, be sure to disconnect the refrigerator from the power supply by removing the plug from the outlet. Working with live electrical components is strictly prohibited by safety rules.
☑️ Tools for testing
Get access to the thermostat. In two-compartment models, it is usually located inside the refrigerator compartment in the upper right corner, hidden behind a plastic panel or directly under the temperature control knob. Sometimes access requires partially dismantling the top cover of the refrigerator or removing the lampshade.
It is important to ensure good lighting of the work area, since wires and terminals may be located in hard-to-reach places. If you are testing in an unheated room in winter, let the device warm up to room temperature to eliminate the effect of condensation on the contacts.
Visual inspection and initial check of contacts
After removing the protective casing, you will see the thermostat itself - this is a plastic block with a long capillary tube coming out of it, which goes deep into the body. First of all, inspect the condition of the external contacts and suitable wires. There should be no traces of burning, insulation melting or oxidation.
Pay attention to the fastening of the capillary tube. It should fit snugly against evaporator or a special plate inside the chamber. If the tube is loose or misaligned, the thermostat will read the wrong temperature, causing the entire system to malfunction. In such cases, replacement may not be necessary - it is enough to install the sensor correctly.
⚠️ Attention: The capillary tube of the thermostat is very thin and fragile. If handled carelessly, it can easily be damaged, which will lead to gas leakage and complete inoperability of the new part. Be extremely careful.
Check the integrity of the insulation of the wires going to the relay terminals. If you find cracks or abrasions, they will need to be sealed before further testing. Often the cause of the malfunction is not the mechanism itself, but poor contact at the junction of the wire with the terminal due to vibration or corrosion.
Nuances of the design of the capillary tube
The capillary tube is filled with an inert gas or freon, which expands when heated and contracts when cooled. This change in volume is transmitted to a membrane inside the relay, opening or closing the contacts. If the tube is pinched or has microcracks, the gas evaporates and the relay stops responding to temperature. It is impossible to restore the tightness in a domestic environment; only replacement is required.
Method of checking a thermostat with a multimeter
The most reliable diagnostic method is to test the contacts using a multimeter. To do this, you need to remove the terminals from the thermostat terminals. Take a photo of the connection diagram first so that you don’t mix up the wires during assembly. Usually there are two or three of them, depending on the model Atlant.
Switch the multimeter to the resistance measurement mode (Ohm) or to the continuity mode. Touch the probes to the relay contacts. If the thermostat is working properly and is at room temperature, the device should show a resistance close to zero or emit a sound signal. This means that the circuit is closed and current can pass.
Next, you need to check if the circuit is open. To do this, the thermostat needs to be cooled. The easiest way is to place it in the freezer for 15-20 minutes (pre-pack it in a bag to prevent moisture from getting in). After cooling, repeat the measurement: If the resistance remains zero (the circuit is closed), the thermostat is faulty, the contacts are “stuck.” shows jumping values - there is an unstable contact inside, the part requires replacement.
- 📉 If the resistance remains zero (the circuit is closed), the thermostat is faulty, the contacts are “stuck.”
- 📈 If the resistance has become infinite (the circuit is open) - the thermostat is working, it reacts to the cold.
- ⚡ If the device shows jumping values, there is an unstable contact inside, the part requires replacement.
However, Atlant refrigerators are characterized by a circuit where at room temperature the contacts are closed (the compressor must work), and when strongly cooled they open (brake signal).
Comparative table of symptoms and solutions
For ease of systematization of the received data, use the following table. It will help you compare the behavior of your refrigerator with typical faults and choose the right solution.
| Symptom | Multimeter readings | Probable cause | Solution |
|---|---|---|---|
| The refrigerator does not turn on | Infinite resistance at room temperature | Open circuit inside the thermostat | Replacing the thermostat |
| Continuous operation | Zero resistance after freezing | Contacts stuck in closed state | Replacement of thermostat |
| Short operating cycles | Resistance jumps | Unstable contact or burning | Replacing the thermostat |
| Incorrect temperature conditions | The circuit works, but with a delay | Displacement of the capillary tube | Adjusting the position of the tube |
Analyzing the table, you can see that in the vast majority of cases, in the event of an electrical fault, only replacement of the parthelps. Repairing the internal contacts of the thermostat in domestic conditions is impractical due to low reliability and complexity of calibration.
If the multimeter shows that the electrical part is working, but the refrigerator behaves strangely, the problem may lie in the mechanical part - for example, in a weakened spring or a broken bellows. In this case, it is also recommended to install a new component.
Replacing the thermostat: step-by-step algorithm
If diagnostics confirm a malfunction, it is necessary to replace it. Buy a similar model of thermostat, paying attention to the markings and length of the capillary tube. For two-chamber Atlantov relays of the TAM or K-59 series are often used, but it is better to look at the exact number in the device passport.
The replacement process begins with dismantling the old device. Carefully disconnect the wires, remembering their location. Then remove the capillary tube from the mounting hole in the chamber wall. Be careful not to damage the internal circuit of the refrigerator.
⚠️ Attention: Do not attempt to shorten or lengthen the capillary tube of the new thermostat. This will disrupt the calibration and result in incorrect operation. If the tube is longer, it can be carefully rolled into a ring inside the chamber.
Install the new thermostat in the reverse order: first fix the tube, then connect the wires according to the diagram or photograph made earlier. Make sure all terminals are tight and not loose. After assembly, turn on the refrigerator and monitor its operation for several hours.
Frequently asked questions (FAQ)
Is it possible to temporarily bypass the thermostat so that the refrigerator works?
Technically, you can short the wires directly and the compressor will work constantly. However, this is extremely risky: the refrigerator will not turn off, the temperature will drop below zero, the food will spoil, and the compressor may burn out from overload. Use this method only for a short-term check of the motor.
Why does the new thermostat not click?
Some modern electronic or specific mechanical thermostats operate silently. If the multimeter shows a change in resistance with a change in temperature, then the part is working, even if you do not hear a characteristic click.
How to determine how long the capillary tube should be?
The length of the tube depends on the model of the refrigerator. Ideally, you need to buy a part with the same markings. If there is no exact analogue, it is permissible to use a longer tube (the excess is carefully laid out), but a shorter tube may not reach the temperature control zone.
Is it necessary to defrost the refrigerator before replacing the thermostat?
Yes, complete defrosting is required. This will prevent water from getting on the electrical contacts during operation and will make it possible to safely remove the capillary tube from the icy channel.