A sudden stop in the operation of refrigeration equipment or, conversely, its endless freezing cycle often indicates a failure of one of the key temperature control elements. In brand models Atlant, which are popular due to their reliability, such a part is a thermostat. It is this small device that is responsible for turning the compressor on and off depending on the temperature inside the chambers.
Before calling a technician or buying expensive spare parts, it is worth carrying out the initial diagnostics yourself. Checking the thermostat is a procedure available to any home craftsman who has basic skills in working with tools and a minimum set of equipment. Correct identification of the fault will help save significant money and time.
In this article we will analyze in detail the design of the system, symptoms of failure and instrumental testing methods. You will learn how to safely dismantle the unit, what parameters to measure with a multimeter and what to pay attention to during a visual inspection. Timely replacement The defective part will restore the normal operation of your refrigerator.
Operation principle and main symptoms of the malfunction
A temperature regulator, or thermostat, is an electromechanical device that closes or opens the electrical power supply circuit to the compressor. Inside the device there is a bellows tube filled with a temperature-sensitive gas (freon). When the temperature in the chamber rises, the gas expands, the pressure in the tube increases, and the contacts close, starting the motor.
Understanding this process is important for diagnostics. If the mechanism is stuck in a closed state, the compressor works non-stop, trying to achieve unattainable cold. Otherwise, when the contacts do not close, the refrigerator simply remains silent, and the food begins to deteriorate. Thermostat malfunction is one of the most common causes of such failures.
The problem can be identified by characteristic signs that appear long before the unit completely stops. Careful observation of the behavior of the equipment will help to localize the breakdown unit even before disassembly.
- ❄️ The compressor works continuously, without turning off for hours, and the temperature in the chamber drops below normal, the food freezes.
- 🔇 The refrigerator is completely silent, the indicators are on, but the engine does not start even after defrosting.
- 🌡️ The temperature regime changes chaotically: either too cold, then too warm, although the regulator settings have not changed.
- 💡 Traces of oxidation, rust or mechanical damage are visible on the thermostat body or at the place where the capillary tube is attached.
⚠️ Attention: If the refrigerator makes loud clicks when trying to start, but the compressor does not start, the problem may lie not only in the thermostat, but also in the start relay or the motor itself. Do not rush to change all the parts at once.
It is important to note that in modern models with a system No Frost and electronic control, the thermostat functions are often performed by a temperature sensor (thermistor), which is checked differently. In this article we consider mechanical thermostats typical of classic two-chamber models Atlant.
Preparation for diagnostics: tools and safety
Any work with electrical appliances requires compliance with safety rules. The refrigerator is a high voltage device and careless handling of the wiring may result in electric shock or short circuit. Before starting any manipulations, it is necessary to completely de-energize the unit.
To carry out high-quality diagnostics, you will need a minimum set of tools. The main requirement is the serviceability of the measuring device. If the multimeter shows incorrect values on obviously working elements, diagnostics will be useless.
☑️ Preparing to check the thermostat
Here is a list of necessary equipment for the job:
- 🔧 Multimeter (digital or analog) for measuring resistance and continuity of the circuit.
- 🪛 A set of screwdrivers (phillips and flat) for dismantling panels and casings.
- 🧤 Dielectric gloves for additional protection when working with contacts.
- 📸 Smartphone with a camera to photograph the wiring diagram in front of them disconnection.
After unplugging the refrigerator from the outlet, you must wait until the residual charge drains from the capacitors (usually 5-10 minutes). Only after this can you begin to remove the protective panels. In models Atlant the thermostat is most often hidden under a plastic cover in the upper part of the refrigerator compartment or inside the lampshade.
⚠️ Attention: Never measure resistance or continuity on a device connected to the power supply. This is guaranteed to burn out the fuses of the multimeter or the device itself.
Removing the thermostat in Atlant refrigerators
Access to the thermostat in different models Atlant may differ. In classic two-chamber refrigerators, it is usually located outside, under the top lid of the refrigerator compartment, or inside, behind the lampshade. Some modifications require removal of the entire top panel.
The dismantling process requires care, since plastic elements can be fragile, especially if the refrigerator has been in use for a long time. The bellows tube coming from the thermostat is very thin and is easily damaged if handled carelessly.
Consider the standard algorithm of actions for gaining access to the contact group:
- Release the top shelf of the refrigerator compartment for ease of operation.
- Carefully pry and remove the plastic casing hiding the thermostat and lamp.
- Unscrew the mounting screws holding the thermostat housing (if any).
- Take a photo of the location of the wires connected to the terminals so as not to confuse them during assembly.
- Disconnect the terminal blocks by slightly rocking them from side to side to the side.
Features of removing the bellows tube
The bellows tube is not screwed, but is inserted into a special socket or pressed with a bar. You cannot pull it with force - you can break the tightness of the system. In some Atlant models, the tube is simply removed from the seat after removing the fixing bracket. If the tube is glued, use a hair dryer to soften the glue, but do not overheat the plastic.
After disconnecting the wires, the thermostat can be removed from the niche. Pay attention to the device labeling. For models Atlant regulators of the series TAM (for example, TAM-133) or imported analogues Danfoss, Thermoare often used. Write down this data if you are planning to purchase a new part.
Methods for checking the health of the thermostat
There are several ways to check the functionality of the thermostat. The most accurate and reliable is to use a multimeter in resistance (Ohm) or continuity measurement mode. This method allows you to objectively assess the condition of contacts.
The first stage of verification is visual. Inspect the housing for cracks, and the contacts for carbon deposits or oxides. If the contacts are blackened, this may indicate a spark slipping and sticking, which requires replacement of the unit.
The main check is performed according to the following algorithm:
- 📏 Set the multimeter to resistance measurement mode (200 Ohm range) or continuity mode.
- 🔌 Connect the multimeter probes to the main contacts of the thermostat (usually these are pins 3 and 4, but it is better to check the circuit diagram of the specific device).
- ❄️ At room temperature, the contacts should be closed (the device beeps or shows resistance close to zero).
- 🧊 Place the sensitive part of the thermostat (bellows tube) into a container with cold water with ice for 2-3 minutes.
- 🔊 After cooling, the contacts should blur (resistance tends to infinity, continuity is silent).
If the contacts do not open during cooling, it means that the thermostat is “stuck” and requires replacement. If they do not close even when heated, the spring of the mechanism has weakened or broken. In both cases, repair is impossible; installation of a new regulator is required.
Comparative table of symptoms of malfunction
To simplify diagnostics, we suggest that you familiarize yourself with the summary table, which will help compare the observed symptoms with the probable causes. This will allow you to quickly make a decision about the need to replace the part.
| Symptom | Probable cause | Action | Result of checking with a multimeter |
|---|---|---|---|
| The refrigerator does not turns on | Open thermostat circuit | Checking contacts | Infinite resistance at any temperature |
| Continuous operation of the compressor | Sticking contacts | Bellows cooling | Resistance is close to zero even after freezing |
| Short operating cycles | Incorrect calibration | Replacement or adjustment | Contacts open too early |
| Sparking inside the chamber | Burning of contacts | Urgent replacement | Unstable readings, resistance surges |
It is worth considering that in some cases the problem may not be in the thermostat itself, but in a refrigerant leak. If there is little freon in the system, the pressure does not increase, and the thermostat simply does not receive a signal to turn on, although formally it is working. A critical sign of a leak is the lack of cold in the evaporator when the compressor is running or the complete absence of motor operation when the thermostat is working.
Replacing and setting up a new regulator
If Diagnostics confirmed the malfunction, the only solution is replacement. When purchasing a new part, pay attention not only to the model, but also to the length of the bellows tube and the location of the contacts. There are no universal solutions; each thermostat has its own parameters.
Installation is carried out in the reverse order of dismantling. It is important to properly secure the bellows tube in the evaporator. It should fit tightly to the surface through the standard hole, but not rest against the back wall too much so as not to damage it.
After installing and connecting the wires, you need to configure:
- 🔧 Set the regulator knob to the middle position (usually the number 3 or 4).
- ⏳ Turn on the refrigerator at network and let it work for 2-3 hours without loading food.
- 🌡️ Check the temperature in the chamber using an external thermometer.
- ⚙️ If necessary, adjust the position of the handle, turning it towards increasing or decreasing the cold.
In models Atlant with two compressors, the procedure is repeated for each circuit separately. Remember that the thermostat of the refrigerator compartment and freezer compartment (if it is mechanical) are different devices with different temperature thresholds.
Frequently asked questions (FAQ)
Is it possible to repair a thermostat if it is broken?
At home, thermostat repair is impossible. This is a sealed unit filled with gas under pressure. Opening the case will lead to depressurization and final failure. The only option is to replace it with a new one.
Why did the refrigerator start working longer after replacing the thermostat?
The new thermostat may have slightly different calibration data. Let the refrigerator operate normally for a day. If the cycle does not normalize, it may be necessary to adjust the screw under the handle or check the door for tightness.
What is the difference between the TAM-133 thermostat and the TAM-145?
The main difference is the length of the bellows tube and the temperature range of operation. TAM-133 is more often used in the refrigerator compartment, and TAM-145 in the freezer compartment. Installing the wrong model will lead to incorrect operation.
How to understand that the problem is not in the thermostat, but in the compressor?
If you close the contacts of the thermostat directly (bypassing it), and the compressor starts and starts cooling, the problem is in the thermostat. If the motor hums but does not start, or does not respond at all, the problem is in the start relay, the motor, or lack of refrigerant.
Do you need to defrost the refrigerator before checking?
Full defrosting is not necessary to check the electrical circuit, but is advisable if you are planning a replacement so that water does not get into the contacts. To accurately diagnose the operation of the bellows, it is better that the evaporator is clean and dry.