Refrigerators Atlant series 59, such as the popular models MHM-2808, MHM-2819 or MHM-2823, have served faithfully in many homes for decades. However, like any complex mechanism, they are subject to wear, and one of the most common problems is the failure of the thermostat. When the compressor stops turning off or, conversely, does not start at all, and the temperature in the chambers no longer corresponds to the set values, most often this particular unit becomes the culprit.
Replacing the thermostat is a procedure that can be performed independently if you follow caution and safety precautions. Critical important before starting any work, completely disconnect the refrigerator from the electrical network. This is not just a recommendation, but a prerequisite, since you will be working with live conductive elements. In this article we will analyze in detail the process of diagnostics, dismantling the old sensor and correctly connecting the new thermostat.
For successful repairs you will need a minimum set of tools: Phillips and flat-head screwdrivers, pliers and, preferably, a multimeter to test the circuit. If you have never dealt with the repair of household appliances before, do not rush to immediately disassemble the unit. First, make sure that the problem really lies with the thermostat and not with a freon leak or a faulty start relay. Correct diagnostics will save you time and money on purchasing unnecessary spare parts.
Diagnostics of thermostat malfunction
Before proceeding with replacement, you need to make sure that the thermostat is faulty. Symptomsindicating a breakdown may be different. Most often, users notice that the refrigerator “cries” (water accumulates inside), food in the freezer begins to melt, or, conversely, everything freezes even with the minimum setting of the regulator knob. The compressor can work without interruption, hum around the clock, or remain silent, despite the fact that the chamber is warm.
The most reliable way to check is to “freeze” the sensor. To do this, you need to dismantle the thermostat, place its sensitive tube (capillary) in a container of water and place it in the freezer for 10-15 minutes. After this, without removing it from the cold, test the contacts with a multimeter. If the circuit does not close (there is no sound signal), then the mechanism is “stuck” and requires replacement. If there is a click and there is zero resistance, let the sensor warm up to room temperature - the contacts should open.
⚠️ Attention: The capillary tube of the thermostat is very thin and filled with refrigerant. If handled carelessly or bent, it may burst, which will lead to gas leakage and complete inoperability of the sensor. Handle it with extreme care, do not squeeze it with pliers or jerk sharply.
It is also worth paying attention to the condition of the contacts. If, during a visual inspection, you notice carbon deposits, melting of plastic or oxidation of the terminals, this is a sure sign that the thermostat was operating in emergency mode for a long time or that an increased current was passing through it. In such cases, replacement is mandatory, even if the continuity test shows a short circuit, since the reliability of the restored unit will be in question.
Removing the old thermostat in Atlant 59
The process of removing the thermostat in refrigerators Atlant series 59 has its own design-related features lighting lamp. Unlike older models, where the sensor was mounted externally, here it is often integrated into the control system inside the refrigerator compartment. To begin, remove the top cover of the lampshade, which is usually held on by latches or one self-tapping screw hidden under a decorative plug.
After removing the lampshade, you will see an electronic board or mechanical unit to which the wires fit. The thermostat can be mounted on a bracket or inserted into a special socket. Carefully disconnect the wire connectors. Remember or, much better, take a photo of the connection diagram before disconnecting the wires. The color marking may differ depending on the year of manufacture of the refrigerator, and an error here is unacceptable.
☑️ Preparation for dismantling
The most delicate part of the process is removing the sensitive tube from the evaporator. It is inserted into the technological hole and can be glued or fixed with a clamp. In some modifications of the series 59, the tube is simply inserted into a socket in the chamber wall. You need to pull smoothly, without jerking, slightly turning the tube around its axis. If you feel strong resistance, check whether it is glued and, if necessary, carefully cut off the layer of sealant.
Connection diagram and color coding of wires
Correct connection of the thermostat is the key to successful repair. Refrigerators Atlant use standard color coding, but it is always better to double-check the correspondence of the contacts according to the diagram of a specific device. There are three main wires: one goes from the network (phase), the second goes to the compressor, and the third goes to the light bulb (if it is connected through a thermostat, which is typical for mechanical models) or to the defrost sensor.
Below is a table that will help you navigate the purpose of the wires. Please note that insulation colors may vary in different modifications, so rely primarily on the location of the terminals and markings on the body of the thermostat itself.
| Contact on the thermostat | Wire color (typical) | Where the wire goes | Function |
|---|---|---|---|
| 3 (or L) | Red / Brown | Network (220V) | Power supply |
| 4 (or 1) | Black / Green | Compressor | Engine start |
| 6 | White / Yellow | Lamp / Sensor | Lighting or defrost |
| Grounding | Yellow-green | Housing | Safety |
What to do if the colors of the wires do not match the table?
If the color The markings of the wires in your refrigerator are different from the standard ones, do not act at random. You need to find the electrical diagram, which is often pasted on the inside wall of the refrigerator or in the technical data sheet. You can also trace the path of each wire: the wire that goes directly into the engine compartment to the start relay is most likely a phase wire for the compressor. The wire going to the lamp shade is responsible for lighting. If you are not confident in your abilities, it is better to call a technician, as incorrect connection can lead to a short circuit.
When connecting a new thermostat, make sure that the contacts fit tightly in the sockets. Poor contact will lead to sparking, heating and eventual melting of the plastic. If the terminals on the wires are oxidized, it is better to replace them or clean them until they shine. For reliability, you can use dielectric grease, which will prevent corrosion of the contacts in conditions of high humidity.
Installing a new thermostat
Installing a new temperature sensor is carried out in the reverse order of dismantling. First, carefully insert the capillary tube into the process hole of the evaporator. The immersion depth should be the same as that of the old sensor - usually it is 10-15 cm, but it is better to be guided by the bend of the tube or marks. Do not allow kinks in the tube, this can disrupt its operation.
Fix the thermostat housing to the seat. In models Atlant 59 it is often fixed with a screw or special claws. Make sure that the housing does not loosen or vibrate when the compressor is running, as vibration may cause false operation or damage to the contacts. Connect the wires according to the diagram tested earlier.
After connecting all electrical circuits, reinstall the lampshade and decorative trims. Do not rush to immediately plug in the refrigerator. Let it sit unplugged for another 10-15 minutes to ensure all connections are secure and nothing is forgotten. Only after the final check can you begin testing.
Configuring and testing operation
After turning on the refrigerator, the compressor should start working almost immediately (if the temperature in the chamber is higher than the set one). Let the unit run for 30-40 minutes. During this time, the temperature in the refrigerator compartment should begin to decrease. At the initial stage, it is better to set the thermostat knob to the middle position (usually number 3).
Watch the cyclical operation. The normal mode for a working refrigerator is to operate the compressor for 10-15 minutes and then rest for 10-20 minutes (depending on the load and ambient temperature). If the compressor runs continuously for more than an hour and does not turn off, the new thermostat may be faulty, incorrectly set, or there is not enough refrigerant in the system.
Check the temperature in the main chamber using an external thermometer. It must correspond to the set value on the regulator knob. If the refrigerator “does not freeze” to the required values even at maximum, or, conversely, freezes food at minimum, additional adjustment may be required with the screw on the thermostat housing, although new factory sensors usually do not need this.
Frequent connection errors
One of the most common mistakes is ignoring the condition of the door seals. If you replace the thermostat, but the door does not close tightly, the refrigerator will not work correctly, and the new sensor will quickly fail or the compressor will constantly run. Tightness chambers are a key factor in effective operation.
Another mistake is using the wrong analogue. Thermostats for Atlant series 59 have a specific capillary length and temperature range. Installing a sensor from another model (for example, from a more powerful two-compressor refrigerator) will lead to incorrect operation: either the chamber will be overcooled, or the compressor will turn on too rarely.
⚠️ Attention: Technical characteristics of thermostats may vary depending on the batch and component manufacturer. Always check the markings on the new sensor with the markings on the old one. If you are not sure of compatibility, contact official spare parts catalogs or consultants at specialized stores.
They also often forget to check the compressor start relay when replacing the thermostat. If the relay is “tired”, it may not start the engine even with a working sensor, creating the illusion of a broken thermostat. An integrated approach to diagnostics will allow you to avoid repeated disassembly of the refrigerator.
FAQ: Frequently asked questions
Is it possible to use a thermostat from another refrigerator if the original one is not on sale?
You can use an analogue, but only if its parameters (temperature range, capillary length, type fastenings) coincide with the original. Installing an incorrect sensor may result in food spoilage or compressor failure. It is better to look for the original spare part number (for example, TAM-133 or its analogues for Atlant).
Why did the refrigerator start working longer after replacing the thermostat?
This may be due to several reasons: the temperature is set incorrectly, the door does not close tightly, the condenser at the back of the refrigerator is dirty, or the new thermostat has a slightly different response range. Let the refrigerator operate for a day in normal mode to stabilize.
Do you need to defrost the refrigerator before replacing the thermostat?
Full defrosting is not necessary if you work quickly. However, if there is a lot of ice in the evaporator, access to the service port may be difficult. In this case, it is better to defrost the chamber in order to carefully remove and install the capillary tube without damaging the walls of the evaporator.
Where is the adjustment screw on the thermostat?
Many mechanical thermostats have a small adjustment screw, often sealed with paint. It is not recommended to turn it without special equipment and knowledge, as it can reset the factory settings. New sensors are usually sufficient without additional adjustment.