Failure of the thermoregulation system is one of the most common causes of failure of refrigeration equipment, leading to food spoilage. If your unit stops turning off, works without interruptions, or, conversely, stops freezing, then most likely the problem lies in the temperature sensor. Thermoregulator (or thermostat) is responsible for turning the compressor on and off, maintaining the set temperature inside the chambers.
Replacing this yourself element allows you to significantly save on service center services, since the procedure does not require highly complex equipment. However, before starting work, you need to clearly understand the structure of your refrigerator, be it a classic one, a modern one, or a retro model. In this article we will analyze all the nuances of diagnostics, selection and installation of a new regulator. Atlant, modern Indesit or retro model ZIL. In this article we will analyze all the nuances of diagnostics, selection and installation of a new regulator.
It is worth noting that ignoring a thermostat breakdown can lead to more serious consequences, including overheating and combustion of the motor-compressor. In modern models with electronic control, instead of a mechanical thermostat, an air sensor (thermistor) is often used, the replacement principle of which is radically different. Therefore, the first step should always be to accurately identify the type of control of your refrigerator.
Diagnostics of a thermostat malfunction
Before disassemble the equipment, you need to make sure that the problem is in the thermostat. The primary sign of a malfunction is often the absence of a click when turning the temperature control knob to its extreme positions. If you turn the knob, but there is no characteristic sound of turning on or off, this is the first signal of a breakdown.
Another obvious symptom is the continuous operation of the compressor. The unit hums constantly, without going to rest, while in the refrigerator compartment a “snow coat” can form on the back wall, and food can freeze. In the opposite situation, the compressor may not start at all, even if you close the contacts manually.
For a more accurate check, you can use the freezing method:
- 🌡️ Remove all products from the refrigerator compartment and leave the unit on for 5-6 hours.
- 🧊 If for this time, a layer of frost or ice has not formed on the back wall, and the temperature has not dropped, which means the compressor does not receive a signal to start.
- 🔌 Disconnect the refrigerator from the network, find the thermostat and carefully short-circuit the two wires coming from it, bypassing the device itself.
- ⚡ If, after connecting to the network with closed wires, the compressor starts working, the diagnosis is confirmed - The thermostat is faulty.
⚠️ Attention: When performing electrical tests, make sure that your hands are dry and the floor under your feet does not conduct current. Do not touch exposed live wires!
Necessary tools and preparation
Replacing a thermostat is a procedure that requires a minimum set of tools, but maximum care. You don't need expensive specialized equipment; a standard home craftsman's kit is enough. It is important to prepare a workplace with good lighting in advance.
The basic list of tools includes screwdrivers (Phillips and flathead), pliers and, possibly, a multimeter for final testing of contacts. It would also be a good idea to have electrical tape or heat shrink on hand to insulate the connections.
☑️ Preparation for repair
Before starting work, be sure to defrost the chamber, if there is ice in it, and wipe the walls dry. Moisture should not get on the electrical contacts of the new device. It is also recommended to photograph the wiring diagram before disconnecting them, so that there is no confusion when installing a new element.
Removing the old thermostat
The process of removing a faulty element depends on the design of the refrigerator. In most models, the thermostat is located inside the refrigerator compartment, hidden by a plastic panel or lampshade. In some cases, for example, in models Stinol or Indesit, it may be located behind the control panel.
To access the device, you need to remove the decorative plugs and unscrew the mounting screws. Proceed with caution, as the plastic latches on older refrigerators can be fragile. After removing the panel, you will see the thermostat itself with a bellows tube (capillary) suitable for it.
The most delicate part of the process is removing the sensitive tube from the evaporator channel. It may “stick” to the wall or simply sit tightly in the seat.
- 🔧 Gently pull the thermostat towards you, trying not to damage the capillary tube with sharp jerks.
- 🧤 If the tube cannot be removed, you can slightly warm the place where the tube exits the evaporator with a hairdryer (without overheating plastic!) to melt possible ice.
- 🚫 It is strictly forbidden to pull the tube itself, hold only the body of the device, otherwise you can damage the tightness of the bellows.
What to do if the capillary tube breaks?
If during dismantling the capillary tube The thermostat has broken inside the evaporator channel, the situation becomes more complicated. You will need to carefully remove the broken piece using a thin wire with a hook, or, in the worst case, disassemble the back panel of the refrigerator to access the evaporator from the outside. It is often easier and more reliable to install a new thermostat with a longer capillary, carefully laying the excess tube in a snake inside the chamber, if the design allows.
Installation and connection of a new regulator
Installation of the new device is carried out in the reverse order of dismantling. The main requirement is exact matching of the characteristics. The new thermostat should have similar on and off parameters, as well as the length of the capillary tube. The tube is inserted into the same hole until it stops, but without excessive force.
Connecting electrical wires requires care. Color markings may differ between different manufacturers, so you need to rely on the diagram or previously taken photographs. Typically, wires with white, red, orange or black insulation are used.
The standard connection diagram for most mechanical thermostats is as follows:
- 🟢 Green or yellow-green wire - grounding (connected to the case).
- 🔴 Red or orange - phase from the network (input).
- ⚫ Black or white - phase to the compressor (output).
- 🟡 Yellow - often goes to a lighting lamp or fan (in two-chamber models).
After connecting the wires, make sure that the contacts are tightly seated in the terminals. Poor contact will lead to sparking and melting of the plastic. If the old terminals have oxidized or lost their spring properties, it is better to replace them with new ones.
Compatibility and markings table
When choosing a spare part, it is important to pay attention not only to the appearance, but also to the markings. Different manufacturers use their own designations, but many thermostats are interchangeable provided the basic parameters are observed.
The following is a table of correspondence between popular models of thermostats for various brands of refrigerators:
| Original (Brand) | Analogue (TAM, K, RANCO) | Type of application | Capillary length |
|---|---|---|---|
| Atlant, Minsk | TAM-133, K-50 | Single-chamber | 0.73 m |
| Indesit, Ariston | TAM-145, K-59 | Two-chamber | 2.5 m |
| Liebherr, Bosch | K-57, K-56 | C frosty. No Frost camera | 0.75 - 3.0 m |
| ZIL, Saratov | TAM-133, ORU-B | Small car | 0.73 m |
Please note that the length of the capillary tube must be equal to or greater than the original one. If the tube is longer, it can be carefully twisted into a ring and placed inside the refrigerator body, making sure that it does not touch moving parts or very hot elements.
⚠️ Attention: The characteristics of thermostats (on/off temperature) may vary slightly between different analogue manufacturers. After installation, additional adjustment of the rod inside the control knob may be required.Setting up and checking operation
After assembling the housing and connecting to the network, do not rush to load products. The refrigerator needs time to reach operating mode. It is better to perform the initial startup empty, monitoring the temperature using an external thermometer.
Set the adjustment knob to the middle position (usually number 3 or 4). After 30-40 minutes of operation, the compressor should turn off. If this does not happen, and the unit continues to freeze until a thick crust of ice forms, you may need to adjust the screw inside the handle rod.
If the refrigerator does not turn off at all, check whether the capillary is jammed during assembly. Also make sure that the thermostat is not installed “upside down” relative to its standard position, if the design provides for this (some models are sensitive to orientation in space).
Common mistakes when replacing
Despite its apparent simplicity, beginners often make mistakes that negate all the work. The most common of these is incorrect installation of the capillary tube. It should be in close contact with the surface of the evaporator along the entire length of its location in the channel.
Another mistake is ignoring the condition of the door seal. If you replace the thermostat, but the rubber door circuit allows heat to pass through, the refrigerator will work in increased mode, and the new thermostat may quickly fail or “sag” in settings.
Grounding is also often forgotten. The thermostat housing in some models may become energized if the insulation breaks down, so connecting the ground wire (green) to the metal body of the device is a matter of your safety.
Questions and answers (FAQ)
Is it possible to install a thermostat with a longer capillary than the original?
Yes, you can. The main thing is that the length is no less than the original one. Excess tubes are carefully wound into rings and placed inside the refrigerator compartment, usually behind the back wall or in a free corner, so that they do not interfere with air circulation and are not damaged when loading food.
Why does the new thermostat click, but the compressor does not start?
This may indicate a malfunction of the compressor itself, the start relay or power supply circuit break. Check whether voltage is coming to the compressor terminals at the moment of clicking. Also, the problem may be in the protective relay, which tripped due to overheating.
Is it necessary to charge the refrigerator with freon after replacing the thermostat?
No, it is not necessary. A thermostat is an electrical device that is not directly connected to the refrigerant circuit. You do not violate the tightness of the cooling system, so refilling with freon is not required.
How to understand that the thermostat is “lying”?
If the refrigerator turns off too early (for example, at +10°C) or too late (at -10°C), although the handle is in the middle, then the calibration is broken. This can be checked with an external thermometer. In such cases, adjusting the internal screw or replacing the device helps.