Connecting the thermostat in the refrigerator: diagrams, tools and step-by-step instructions

The thermostat (or thermostat) is the “brain” of the refrigerator, responsible for maintaining the set temperature. Its malfunction leads to the fact that the compressor works without stopping, freezes too much or, conversely, does not turn on at all. Replacing the thermostat is one of the most common repair operations that you can do yourself without resorting to the services of a technician. However, errors during connection can lead to compressor failure, short circuit or even fire.

In this article we will look at how to correctly connect the thermostat in refrigerators of different brands (Atlant, Indesit, Biryusa, Stinol), consider circuits for mechanical and electronic models, and also point out typical mistakes that beginners make. We will pay special attention operability check to the new thermostat before installing and testing the system after repair.

If your refrigerator has stopped freezing, and the compressor either does not turn off or does not start, there is an 80% chance that the problem is in the thermostat. But before you run to the store for a new part, make sure that it is not starting relay or capacitorat fault. To do this, just check the resistance of the compressor windings with a multimeter.

1. Types of thermostats: which one is in your refrigerator?

Before you start replacing, you need to determine which thermostat is installed in your model. The connection diagram, the necessary tools and even the diagnostic algorithm depend on this.

All thermostats are divided into two large groups:

• 🔧 Mechanical —equipped with a siphon tube with a refrigerant (usually freon), which responds to temperature changes. When the tube heats/cools, the membrane inside the thermostat is activated, closing or opening the contacts. Such models were installed in refrigerators Stinol, Atlant, Donbass and other Soviet/post-Soviet brands.
• 📱 Electronic — use thermistors or digital sensors. The signal is processed by a microcontroller, which controls the compressor via a relay. Found in modern models Samsung, LG, Bosch etc.

How to distinguish them visually?

• 🔍 A mechanical thermostat has capillary tube (thin copper or aluminum), which is attached to evaporator. On the body there is an adjusting screw with a handle (or a place for its fastening).
• 🖥️ Electronic looks like a board with connectors or a small block with wires leading to sensors. There are no tubes.

Important: some refrigerators (for example, Indesit series C138) may have combined system a mechanical thermostat for the freezer and an electronic one for the refrigerator. In this case, only the faulty unit will have to be replaced.

2. Tools and materials for replacing the thermostat

For work you will need:

• 🔧 Screwdrivers (cross and flat) - for dismantling the control panel and fastenings.
• 🔌 Multimeter - to check the continuity of the circuit and contact resistance.
• 🔥 Soldering iron (power 25–40 W) and solder —if the wires are soldered to the contacts (relevant for older models).
• 🧲 Pliers/stripper —for stripping wires.
• 📏 Heat shrink tube or electrical tape—for insulating connections.
• 🔍 Flashlight — illumination of the internal parts of the refrigerator.
• 📄 Connection diagram —it can be found in the instructions for the refrigerator or on the sticker inside the case.

Also prepare replacement spare part. The thermostat must be complete analogue according to the model and characteristics. For example, Atlant MHM-170 is suitable for TAM-133-1M, and for Indesit C138G — K59-L1355. If you are not sure, take the old thermostat to the store for comparison.

⚠️ Attention: Never buy thermostats “by eye” or based on the “similar” principle. Even if the connectors are the same, the temperature characteristics may differ. This will lead to improper operation of the refrigerator (for example, the freezer compartment will overfreeze, and the refrigerator compartment will underfreeze).

Disconnect the refrigerator from the network and defrost (if required)

Take a photo of the wiring diagram

Check the new thermostat with a multimeter before installation

Prepare tools and consumables-->

3. Thermostat connection diagrams: mechanics vs electronics

The connection diagram depends on the type of thermostat and the model of the refrigerator. Below are typical options.

Mechanical thermostat

In most cases, a mechanical thermostat has 4 contacts (sometimes 3 or 6). Their designations:

• 🔌 3 and 4 —input and output of the compressor power circuit.
• 🔄 6 —general contact (can be marked as C or COM).
• 🔥 1 or 2 —contacts for the lighting lamp (if the thermostat also controls the light).

Typical circuit for refrigerators Atlant, Stinol, Minsk:

🔹 Important: In some models, contacts 3 and 4 can be swapped. Always check the diagram on the thermostat body or in the instructions!

Electronic thermostat

Electronic thermostats are connected via connectors (usually 4–8 contacts). For example, in refrigerators Samsung series RL a block with 6 contacts is used:

• 🔌 1–2 — power (220V).
• 🌡️ 3–4 — signals from temperature sensors.
• 🔄 5–6 — compressor and fan control.

⚠️ Attention: In electronic thermostats Do not confuse the polarity of connecting sensors. If you mix up the wires from the freezer and refrigerator compartment sensors, the control unit will receive incorrect data, which will lead to malfunctions.

How to find the connection diagram for your model?

If the sticker with the diagram inside the refrigerator has worn off, try:

1. Search for instructions for the model on the manufacturer’s website (for example, [atlas of spare parts for Atlant](https://atlant.by)).

2. Take a photo of the old thermostat and ask on the forums (for example, [Mastergrad](https://mastergrad.com) or [Cold+](https://xolod2.ru)).

3. Contact the service center with a request to send the diagram by email (many provide it for free).

4. Step-by-step instructions: how to connect a thermostat in a refrigerator

Let's consider the process using the example of a mechanical thermostat in a refrigerator Atlant. For other models, the algorithm is similar, but the nuances of dismantling the panel may differ.

Step 1: Removing the old thermostat

1. Unplug the refrigerator and defrost (if required).

2. Remove the top cover of the refrigerator (usually it is attached to 2-4 screws at the back).

3. Unscrew the control panel (in some models it is held on by latches - pry it off with a flat screwdriver).

4. Carefully disconnect capillary tube from the evaporator. It can be attached with a clamp or inserted into a special groove.

5. Take a photo of the wire connection diagram or mark them with tape.

6. Disconnect the wires and remove the thermostat.

Step 2: Installing a new thermostat

1. Place the new thermostat in place of the old one and secure it with screws.

2. Connect the wires according to the diagram (see section 3). If the wires are soldered, use a soldering iron.

3. Attach the capillary tube to the evaporator. It should fit snugly, but not be pinched.

4. Reinstall the control panel and top cover.

Step 3: Check operation

1. Plug in the refrigerator.

2. Set the temperature regulator to the middle position (usually 3–4).

3. Check:

• ✅ The compressor should start in 5-10 minutes.
• ✅ After 1-2 hours, the temperature in the chamber should begin to drop.
• ✅ When the set temperature is reached the compressor should turn off.

⚠️ Attention: If the compressor does not start, check:

• 🔌 Correct connection of wires (especially phase and zero).
• 🔧 Integrity of contacts (possibly bad soldered).
• 🛠️ Start relay (sometimes it fails at the same time as the thermostat).

5. thermostat

Even experienced craftsmen sometimes make mistakes that lead to breakdown of the refrigerator. Here are the most common ones:

• ⚡ Phase and zero are reversed. data-i="213">—if it touches the walls of the refrigerator or is pinched, the thermostat will operate with a delay. - leads to a short circuit or burnout of the compressor windings.
• 🌡️ Improper fastening of the capillary tube - if it touches the walls of the refrigerator or is pinched, the thermostat will operate with a delay.
• 🔌 Poor insulation of connections —can cause current leakage or corrosion of the contacts.
• 🔧 Using a thermostat from another model —even if the connectors match, the temperature settings may not be suitable.
• 📉 Untested new thermostat —before installation, be sure to check it with a multimeter (see section 6).

🔹 Practical example: B refrigerator Stinol-101 after replacing the thermostat, the compressor worked without stopping. The reason is that the master connected the contact 4 (output to the compressor) to zero instead of phase. As a result, the circuit was constantly closed and the motor did not turn off.

⚠️ Attention: If after replacing the thermostat the refrigerator begins to freeze less or, conversely, freezes, most likely the capillary tube is installed incorrectly.

6. multimeter before installation

Before installing a new thermostat, make sure that it is working. To do this:

1. Switch the multimeter to resistance testing mode (ohmmeter).
2. Connect the probes to the contacts 3 i 4 (input and output of the compressor).
3. At room temperature, the resistance should be 0 Ohm (contacts closed).
4. Cool the capillary tube (for example, put it in the freezer for 5–10 minutes).
5. After cooling, the resistance should become infinite (contacts are open).

If the thermostat does not respond to temperature changes, it is defective. Return it to the store and get another one.

🔹 For electronic thermostats check is more complicated:

• Test the power circuit (220V) for a short circuit.
• Check the resistance of the sensors (usually 5–50 kOhm with room temperature).
• If possible, connect the thermostat to a power source and check if the relay operates when the temperature changes.

⚠️ Attention: Some electronic thermostats (for example, Danfoss EVM) require calibration after installation. Without it, the refrigerator may. work incorrectly. Look for calibration instructions in the technical documentation.

7. Connection features in refrigerators of different brands

Although the operating principle of thermostats is the same, there are nuances in refrigerators from different manufacturers.

Atlant (MXM, NM, HM)

Most models Atlant use a thermostat TAM-133 or its modifications:

• The capillary tube is attached to the evaporator with a plastic clamp.
• Contact 3 and 4 often marked as L (phase) and M (motor).
• In the freezers there can be a separate thermostat TAM-145.

Indesit (C138, C168, T16)

In refrigerators Indesit there are often thermostats K59-L1355 (for the refrigerator compartment) and K59-L2368 (for the freezer compartment) Features:

• The control panel is attached to latches, there are no screws.
• In some models, the thermostat controls and fan (additional wire).
• The capillary tube can be double (for dual-zone control).

Samsung (No Frost)

In refrigerators Samsung with a system No Frost electronic thermostats are used EVM or SensysFeatures:

• The thermostat controls defrost heater and the fan.
• Temperature sensors are connected via connectors with keys (cannot be confused).
• After replacement, you may need error reset (press and hold the button Freezer 10 seconds).

🔹 Tip: If you are not sure about the thermostat model, look for it on refrigerator serial number on spare parts websites (for example, Partmaster or Spare parts for cold).

8. When is the best time to contact a specialist?

You can replace the thermostat yourself, but in some cases it is better to trust a professional:

• 🔧 If refrigerator electronic control unit (for example, LG Inverter Linear), and the thermostat is part of it.
• ⚡ If after replacing the refrigerator electric shock or the RCD is triggered.
• 🌡️ If the temperature in the chambers does not stabilize 24 hours after replacement.
• 🔥 If it appears during operation burning smell or smoke.
• 📄 If you could not find connection diagram for your model.

The cost of replacing the thermostat in service center - from 1,500 to 3,500 rubles (depending on the model and region). If you are not confident in your abilities, it is better to pay for the work than to risk expensive compressor repairs.

⚠️ Attention: In refrigerators with inverter compressor (for example, Samsung Digital Inverter) the thermostat is integrated into the control board. Replacing it requires reflashing the unit, which is only possible at a service center.

FAQ: Frequently asked questions about connecting a thermostat

Is it possible to replace a mechanical thermostat with an electronic one?

Theoretically, yes, but it will require a complete rework of the control circuit, installation of additional sensors and a power supply. In practice, this is impractical - it’s easier to buy a new refrigerator. The exception is rare cases when a manufacturer produces adapted electronic thermostats for older models (for example, for ZIL or Minsk).

Why does the new thermostat not work?

Reasons several:

1. Defective part (check with a multimeter).
2. Incorrect connection (phase/zero or sensor contacts are reversed).
3. Bad contact at the soldering/twisting points.
4. Faulty compressor or starting relay (the thermostat may be working, but the circuit is open in another place).

Check all connections and repeat the test with a multimeter.

Do you need to defrost the refrigerator before replacing the thermostat?

If the thermostat is mechanical - yes, defrosting is required. The capillary tube must be free of ice, otherwise the new thermostat will not work correctly. For electronic models, defrosting is not necessary, but is recommended for ease of operation.

Which thermostat is suitable for the Stinol-103 refrigerator?

For Stinol-103 is the thermostat suitable? K59-L1031 or its analogs: TAM-133-1M, Ranco K59. The main thing is that they match:

• Refrigerant type (usually R134a or R600a).
• Length of the capillary tube (standard - 1.5–2 meters).
• Temperature adjustment range (usually from -24°C to +8°C).

Is it possible to temporarily connect the wires without a thermostat so that the refrigerator works?

Yes, but this extremely dangerous! If you close the contacts 3 i 4 (phase to the compressor), the refrigerator will work without stopping, which will to:

• Overheating and compressor breakdown.
• Icing of the evaporator.
• Increased power consumption.

Such “repairs” are only permissible for 1-2 hours to check the operation of the compressor. You cannot operate the refrigerator longer without a thermostat!