Sudden increase in temperature in the refrigerator compartment or, conversely, complete freezing of food often indicates a failure of one of the key elements of the control system - the thermostat. This small device is responsible for turning the compressor on and off, maintaining the set temperature. If you notice that the refrigerator has stopped turning off or has stopped cooling altogether, there is a high probability that this sensor needs to be replaced.
The process of replacing the thermostat is accessible even to those who have basic skills in working with tools, but requires strict adherence to safety precautions and sequence of actions. Incorrect connection of wires can lead to a short circuit or failure of the compressor, so it is important to study the device of your model in advance refrigerator. In this article we will look in detail at how to dismantle the old sensor, check the serviceability of the new one and make the correct connection of the contacts.
Before starting the repair, it is necessary to de-energize the unit. Working with live electrical appliances is strictly prohibited. It is also worth preparing your workplace, since in order to access the thermostat in different models of refrigerators you have to disassemble various components: from the lampshade to the internal panel of the freezer.
Diagnostics and preparation of tools
Before disassembling the refrigerator, you should make sure that the problem lies in the thermostat. Sometimes the symptoms of a malfunction may be similar to a freon leak or a broken start relay. If the compressor does not start at all, even with a direct connection, or runs nonstop, ignoring adjustments, most likely the culprit has been found. For diagnostics and subsequent replacement, you will need a minimum set of tools, which most craftsmen have in their homes.
First of all, prepare a multimeter to check the continuity of the circuit. This device will help determine whether the sensor contacts close when the temperature changes. You will also need screwdrivers (Phillips and flathead), pliers, and possibly side cutters for cutting wires if the terminals do not fit. It would be a good idea to prepare electrical tape or heat shrink to insulate the connections.
⚠️ Attention: Before starting any work, be sure to disconnect the refrigerator from the power supply. Waiting for the capacitors to discharge and the pressure in the system to stabilize may take 15-20 minutes.
It is important to select a similar thermostat model. They differ in the length of the capillary tube, operating temperature range and mounting method. The part number is usually stamped on the body of the old regulator. If the marking is erased, look for information in the technical documentation of your refrigerator, be it Atlant, Indesit or Stinol.
Checking the old thermostat with a multimeter in dial mode should show an open circuit at room temperature (for most models) and short circuit when cooling. If the circuit does not close even in the cold, or, conversely, rings constantly, the part must be replaced. Once you have confirmed the diagnosis, you can begin dismantling.
Removing the old thermostat
The location of the thermostat depends on the design of the refrigerator. In older models and units like Saratov or Biryusa it is often located inside the refrigerator compartment, combined with the temperature control knob and the lampshade. In modern two-chamber models, access to it can be hidden behind a decorative panel or located outside, in the upper part of the case.
If the regulator is located inside the chamber, carefully remove the switch handle. It may be a tight fit, so be careful not to break the plastic. Next, unscrew the screws securing the lamp shade and thermostat housing. In some cases, you will need to remove the entire top cover of the refrigerator. After removing the fasteners, access to the electrical contacts and the capillary tube will open.
The capillary tube is a thin copper conductor that is tucked into the evaporator or attached to the chamber wall. It should not be bent at an acute angle or pulled with force, as there is a sensitive liquid or gas inside. Damage to the tube will lead to refrigerant leakage from the control circuit, and the new thermostat will also not work.
☑️ Removal procedure
Take a photo of the wire connection diagram before disconnecting them. The colors of the wires may not match the standard ones, and the markings on the terminals may be erased. Remember which wire went where: this is critical to the correct operation of the system. Typically, three main contacts are used: phase, zero and contact for a lamp or compressor.
Connection diagram and wire color
Understanding the electrical circuit is the key to successful repairs. The thermostat is a simple electromechanical device that opens and closes the compressor power circuit. Despite its simplicity, confusion in the wires can lead to the refrigerator not starting or the light bulb burning out.
Most household refrigerators use the following color coding, although you cannot rely on it alone:
- 🔴 Red, orange or pink —usually this is the phase going from the socket to the thermostat.
- ⚫ Black or brown —wire going directly to the compressor (load).
- 🔵 Blue or white —often used to connect the camera lighting lamp.
- 🟡 Yellow or yellow-green —grounding (less common in older schemes).
However, in different brands, such as Liebherr or LGthe colors may vary. For example, in some models all wires may be the same color, and the only difference is in the terminal markings. The terminals on the thermostat body are often designated by numbers (3, 4, 6) or letters (L, M, C).
| Marking on the terminal | Purpose of contact | Where to connect | Wire color (approximate) |
|---|---|---|---|
| 3 (or L) | Phase input (Line) | From mains/plug | Red / Brown |
| 4 (or C) | Output to compressor | To start relay | Black / Green |
| 6 (or M) | Output to lamp | To lampshade lighting | Blue / White |
| - | Grounding | To the body | Yellow-green |
When connecting a new sensor, make sure that the wires do not touch moving parts and are not tensioned. Insulation of connections must be reliable. Use the factory terminals that came with the new thermostat or quality connectors. Twists and simple electrical tape are not the best solution for the vibration environment of the refrigerator.
What to do if the colors of the wires do not match?
If the colors of the wires on the new and old thermostat do not match, do not act at random. Use the multimeter in dial mode. Find the wire coming from the plug (phase) and connect it to the input terminal (L). Connect the wire going to the compressor to the output contact (C), which closes when cooling. The lamp wire is connected to the corresponding terminal (M), which opens when the door is opened (if such a function is provided for by the design).
Installation of a capillary tube
The mechanical part of the installation is no less important than the electrical one. The capillary tube of the new thermostat may differ in length from the old one. If it is longer, the excess is carefully rolled into a ring inside the case, being careful not to damage it. In short, this is a problem, since the sensor may not reach the temperature control zone.
In models with an open evaporator (grid on the rear wall), the tube is usually inserted into a special sleeve or pressed with a clip to one of the evaporator partitions. It is important to ensure tight contact of the tube with the surface, but without excessive pressure. In modern No Frost systems, the sensor is often located behind a plastic panel inside the chamber and is attached to a special hole.
⚠️ Attention: The capillary tube is very fragile. Do not bend it to a radius of less than 30 mm and do not allow it to be struck. Damage to the tube makes the thermostat unusable.
When installing into the sleeve, make sure it is clean and dry. To improve heat transfer, it is sometimes recommended to drop a little silicone oil or simply make sure that there is no air gap, although in domestic conditions most often the tube is simply tightly fixed with standard fasteners. Incorrect position of the tube will lead to incorrect reading of the temperature: the refrigerator will either undercool the food or work non-stop.
Setup and testing of the system
After the electrical part is assembled and the tube is installed, you can proceed to testing. Don't rush to load products right away. Turn on the empty refrigerator and monitor its operation. The first cooling cycle may take longer than usual as the system must return to normal.
Check whether the compressor turns off when the temperature reaches low. This is easy to determine by ear: the characteristic hum of the motor should stop, and after a while the relay will click. Also check the operation of the lighting lamp: it should light up when the door is opened and go out when closed (if the same thermostat is responsible for this).
If the refrigerator does not turn off, it is possible that the adjustment range of the new thermostat is not the same as required, or the tube is not cooling enough. Some models have an adjusting screw under the seal on the thermostat body, which allows you to adjust the temperature range, but turning it without special equipment and knowledge is not recommended.
Frequent errors during replacement
Even experienced craftsmen sometimes make mistakes that ruin all the work. One of the most common is poor contact in the terminal block. If the wire is not inserted completely or is oxidized, the plastic at the junction will begin to heat up, which can lead to melting and fire.
Another mistake is ignoring the condition of other elements. When changing the thermostat, always visually assess the condition of the start relay and wires. If the insulation of the wires is cracked, they also need to be replaced or properly insulated. Working in conditions of high humidity of the refrigerator compartment quickly destroys poor-quality insulation.
- ❌ Ignoring grounding: if your socket has a ground, make sure it is connected to the refrigerator body.
- ❌ Wire tension: the wires inside the case must lie freely, without tension, so that vibration the compressor has not broken contact.
- ❌ Wrong model: installing a thermostat with a different temperature range will lead to food spoilage or freezing of the chamber.
They also often forget to check whether the door of the newly installed refrigerator does not touch parts. Protruding parts of the thermostat or incorrectly laid wires can prevent the door from closing tightly, which will lead to freezing of the “fur coat” and increased load on the motor.
Questions and answers (FAQ)
Is it possible to install a thermostat from another brand of refrigerator?
Technically possible if they match mounting dimensions, capillary tube length and electrical parameters (current, voltage). However, temperature ranges may differ between manufacturers, which will result in incorrect operation. It is better to look for an original analogue or a universal model with a wide range of adjustment.
Why does the new thermostat click, but the refrigerator does not turn on?
The click means that the contacts are closed, but the current does not pass further. Possible reasons: the compressor starting relay is faulty, the compressor itself has burned out (winding breakage) or poor contact at the junction of the thermostat wires. It is necessary to test the circuit with a multimeter.
How to understand that the capillary tube is too long?
If the tube is too long, it can be carefully rolled into a ring with a diameter of at least 4-5 cm and placed in the free space of the case, avoiding sharp kinks. The main thing is that the sensitive element (extension at the end) is in the temperature control zone and not hanging in the air.
Does it need to defrost the refrigerator before replacing?
Yes, complete defrosting is desirable. This will prevent water from entering electrical contacts when ice melts during repairs and will provide more comfortable working conditions. In addition, in a defrosted state, it is easier to manipulate the internal panels.