How to independently check the thermostat of the refrigerator: 3 working method

The thermostat (or thermostat) is a key element of the refrigerator, which is responsible for maintaining the set temperature. When the sensor fails, the compressor either runs without stopping or does not turn on at all. Result: food spoils, and the electricity bill rises. Checking the refrigerator thermostat is a task that you can handle yourself, without resorting to the services of a specialist. The main thing is to know the signs of a malfunction and be able to use a multimeter.

In this article you will find step-by-step instructions for diagnosing the thermostat in refrigerators Atlant, Indesit, Samsung, LG and other popular brands. We will look at how to test a relay without special instruments, how to ring the contacts with a tester, and what to do if the thermal relay is faulty. You will also find out in which cases repair is possible, and when it is easier to replace the part.

⚠️ Important: Before starting work, unplug the refrigerator and wait until it completely defrosts (if a model with a No Frost system, 10-15 minutes is enough). Working with live electricity is dangerous to life!

Signs of a thermal relay malfunction: when a check is needed

The thermal relay rarely breaks suddenly - usually the malfunction appears gradually. Here are the main symptoms that indicate problems with the thermostat:

• 🔄 The compressor works without stopping — the refrigerator does not turn off even when the minimum temperature is reached. This leads to freezing of the rear wall and increased energy consumption.
• ❄️ The temperature in the chambers does not correspond to the settings —for example, in the freezer +5°C instead of -18°C, or ice forms in the refrigerator compartment.
• ⚡ The compressor does not turn on at all —the refrigerator does not cool, but the light inside is on. This is often accompanied by relay clicks when trying to start.
• 🔥 Thermal protection is triggered —the compressor turns on for a few seconds and immediately turns off. This can be repeated cyclically.
• 📉 Spontaneous temperature change —for example, the refrigerator suddenly defrosts, although the regulator was not touched.

If you observe at least one of these signs, the thermostat is likely to break down is 70-80%. However, similar symptoms can be caused by other malfunctions:

• 🔌 Leakage of refrigerant (freon)
• 🔧 Breakdown of the compressor or start relay
• 🧊 Clogged capillary tube
• 🔋 Malfunction of the electronic control unit (in modern models)

To accurately determine the culprit, you need check the thermal relay. Let's start with the simplest method - without using tools.

Method 1: Checking the thermal relay without a multimeter (express test)

This method is suitable for mechanical thermostats (installed in 90% of refrigerators older than 10 years). You don't need tools - just your hands and patience.

Action algorithm:

1. Unplug the refrigerator and take out all the products.
2. Find the thermostat - usually it is located inside the refrigerator compartment, under the plastic cover next to the temperature regulator. In some models (Samsung RL-33, LG GA-B409), the thermostat may be hidden behind the rear panel.
3. Remove the protective cover (it is secured with latches or one screw). Under it you will see a plastic box with a tube - this is a thermal relay.
4. Carefully remove the tube from the evaporator (it is secured with a clamp or clip).
5. Immerse the tip of the tube in a glass of hot water (temperature ~50-60°C).
6. Plug in the refrigerator and listen:
   • ✅ If after 1-2 minutes the compressor starts, the thermostat is working properly.
   • ❌ If the compressor does not respond, the relay is faulty.

⚠️ Attention: Do not use boiling water - this may damage the capillary tube of the thermostat. Also, do not keep the relay in water for more than 3-4 minutes.

This method works because the thermostat is triggered by temperature changes. Hot water simulates heating inside the chamber, causing the contacts to close and turn on the compressor. If there is no reaction, the part must be replaced.

Method 2: Checking with a multimeter (accurate diagnostics)

If the rapid test did not give an unambiguous result or If you want to be 100% sure, use a multimeter. This method is suitable for all types of thermal relays - both mechanical and electronic.

What you will need:

• 🔧 Multimeter (the simplest model for 300-500 rubles will do)
• 🔨 Screwdriver (phillips or flat, depending on the model refrigerator)
• 📝 Pliers (for removing terminals)

Check procedure:

1. Disconnect the refrigerator from the network and remove the protective casing of the thermal relay (as in the first method).
2. Inspect the wires suitable for relay Usually there are 3-4 of them:
   • Red/orange —phase from the compressor
   • Brown/black —zero
   • Yellow/green —grounding (if yes)
   • White/gray —signal wire from the temperature sensor (in electronic models)

Remove the terminals from the thermal relay contacts. Remember or take a photo of their location!

Switch the multimeter to resistance testing mode (ohmmeter) or continuity test.

Connect the probes to the contacts 3 and 4 (usually these are the terminals responsible for closing/opening the circuit). In a working relay at room temperature, the resistance should be 0 Ohm (short circuit).

Immerse the capillary tube of the thermorelay in hot water (~50°C). The contacts should open, and the resistance on the multimeter screen will become infinite (1 or OL).

Take the tube out of the water and let it cool. The contacts should close again (resistance 0 Ohm).

Table: Test results with a multimeter

⚠️ Attention: In electronic refrigerators (Samsung RB-30 J3200, LG GB-B399SLQZ) the thermal relay can be integrated into the control board. In this case, checking with a multimeter is pointless - you need a special tester or diagnostics at a service center.

Method 3: Checking the thermal relay with temperature simulation (for advanced)

This method is suitable if you are not sure of the results of previous tests or want to test the thermal relay under conditions as close as possible to real ones. You will need:

• 🔧 Multimeter
• 🧊 Ice or freezer
• 🔥 Hairdryer (you can get by with hot water)
• 📏 Thermometer (optional, for accuracy)

Instructions:

1. Remove the thermostat from the refrigerator as described above. Disconnect the capillary tube from the evaporator.
2. Place the tube in the freezer (temperature ~-18°C) for 10-15 minutes. The thermal relay contacts should closed (resistance 0 Ohm).
3. Take out the tube and heat it with a hairdryer (or immerse it in hot water). The contacts should open (resistance ∞).
4. Repeat the cycle 2-3 times. In a working relay, the closing/opening should occur clearly at a certain temperature (usually for a refrigerator and a freezer). If the contacts operate chaotically or do not respond to temperature changes, the thermostat is faulty. Also pay attention to: +4…+6°C for the refrigerator compartment and -14…-16°C for the freezer).

If the contacts operate chaotically or do not respond to temperature changes, the thermostat is faulty. Also pay attention to:

• 🔍 External damage —cracks on the body, oxidation of contacts, frayed wire insulation.
• 💧 Leakage of freon from capillary tube —if the tube bursts, the thermostat will not respond to temperature.
• 🔌 Quality of terminal fastening —oxidized or poorly secured wires can simulate a relay malfunction.

Critical information: In refrigerators with a No Frost system (for example, Indesit DF 4180, Beko CN 335120), the thermal relay is often paired with a sensor defrosting. If checking the relay shows serviceability, but the refrigerator does not freeze, the problem may be in the defrost sensor or timer.

Where is the thermostat located in refrigerators of different brands

The location of the thermostat depends on the model and type of refrigerator. Here are typical installation locations for popular brands:

• 🔹 Atlant, Biryusa, Nord: inside the refrigerator compartment, under the plastic cover next to the temperature controller. Often attached to one screw.
• 🔹 Indesit, Ariston: in the upper part of the refrigerator compartment, on the right or left. In models with electronic control (Indesit BIAA 13), the thermostat may be on the back wall, under the cover.
• 🔹 Samsung, LG: in refrigerators with a display, the thermostat is integrated into the control board (behind the rear panel). In mechanical models (Samsung RT-22) - under the temperature regulator.
• 🔹 Beko, Vestfrost: in the freezer compartment (for two-compressor models) or under the top shelf of the refrigerator compartment.
• 🔹 Liebert, Stinol: the thermostat can be moved outside the chamber and located on the evaporator tube (rear refrigerator).

In refrigerators with a No Frost thermal relay system, they are often installed next to the fan or defrosting heating element. In two-chamber models there may be two thermostats separately for the refrigerator and freezer compartments.

🔍 How to quickly find a thermostat?

1. Open the refrigerator compartment and inspect the inner walls for a plastic cover measuring 5x5 see
2. If there is no cover, check the back wall of the chamber (in some models LG the thermostat is hidden under the panel).
3. In mechanically controlled refrigerators, the relay is always located next to the temperature control knob.

What to do if you can’t find thermal relay?

In some models (for example, Samsung RL-38 or LG GA-B459) the thermal relay is hidden under the egg tray or behind the decorative panel. If a visual inspection does not help, look for technical documentation for your refrigerator model. Typically, diagrams of the location of parts are in the user manual or on the manufacturer’s website.

What to do if the thermal relay is faulty: repair or replacement?

If the check shows that the thermal relay is faulty, you have two options:

1. Repair —possible only in case of mechanical damage (oxidation of contacts, broken wires). To do this:
   • Clean the contacts with sandpaper or a file.
   • Check the integrity of the capillary tube - if it is damaged, the relay cannot be repaired.
   • Make sure that the wires are securely fastened on the terminals.

Replace —the best option in 90% of cases. A new thermostat costs from 500 to 2000 rubles, depending on the refrigerator model.

How to choose a new thermostat?

Thermostats differ in several parameters:

• 🔧 Type of fastening - on screws, latches or clips.
• 📏 Length of capillary tube - must match the original (usually 1.5-2.5 meters).
• 🔢 Temperature range - for the fridge compartment (-10…+10°C), for the freezer (-30…-10°C).
• 🔌 Connection diagram —number and location of terminals.

🔍 Where to buy?

• 🛒 In specialized spare parts stores for household appliances (for example, “220 Volt”, “Techport”).
• 🌍 On marketplaces - Wildberries, Ozon, AliExpress (but be careful with counterfeits!).
• 🔧 In refrigerator repair service centers - they often sell used parts in good condition condition.

How to replace the thermal relay yourself?

1. Disconnect the refrigerator from the network.
2. Remove the old relay, remembering the location of the wires (better to take a photo!).
3. Install a new relay by connecting the wires in the same order.
4. Attach the capillary tube to the evaporator (it should fit tightly to the metal).
5. Close the protective casing and turn on the refrigerator.

⚠️ Attention: In refrigerators with electronic control (Samsung RL-44, LG GB-B539), replacing the thermal relay may require reflashing the board. In this case, it is better to contact. to the technician.

Frequent errors when checking and replacing the thermostat

Even experienced craftsmen sometimes make mistakes that lead to repeated breakdowns or incorrect operation of the refrigerator. Here's what you can't do:

• ❌ Check the thermostat without disconnecting the refrigerator from the mains - it's life-threatening! disconnecting the refrigerator from the network
• ❌ Use a voltage above 220V for testing - this can burn the relay contacts.
• ❌ Shorten or lengthen the capillary tube - this will disrupt the calibration of the thermostat.
• ❌ Install a thermal relay from another model “similar in appearance" —even if the terminals are the same, the temperature range may differ.
• ❌ Ignore contact oxidation —poor contact can simulate a relay malfunction.

🔧 Typical problems after replacing the thermal relay:

• The refrigerator does not turn on —check that the wires are connected correctly (possibly phase and neutral are reversed).
• The compressor works without stopping —the thermal relay is incorrectly calibrated or the capillary tube does not fit well evaporator.
• The temperature in the chambers does not correspond to the settings —a relay with the wrong temperature range may be installed.

If problems remain after replacement, do not rush to blame the new one relay. In 30% of cases the reason lies in:

• 🔌 Faulty compressor or start relay.
• 🧊 Freon leakage (required refueling).
• 🔧 Breakdown of the electronic control unit (in modern models).

FAQ: Answers to frequently asked questions

Is it possible to check the thermal relay without removing it from the refrigerator?

Yes, but only in refrigerators with mechanical control. To do this:

1. Disconnect the refrigerator from the network.
2. Remove the terminals from the thermal relay (they are usually located under the plastic cover).
3. Ring the contacts 3 and 4 with a multimeter in dialing mode.
4. If at room temperature the circuit is closed (resistance 0 Ohm), and when the tube is heated with a hairdryer it opens, the relay is working properly.

However, this method is less accurate, since you cannot simulate real operating conditions.

How to check thermal relay in a refrigerator with electronic control?

In refrigerators with a display (Samsung RB-37, LG GA-B489), the thermal relay is often integrated into the control board. Checking with a multimeter is pointless - diagnostics is needed using a special tester or computer. Signs of a malfunction:

• An error is displayed on the display (for example, Er IF or Er dS).
• The refrigerator does not respond to temperature changes from the control panel.
• The compressor turns on for 5-10 seconds and immediately turns off.

In this case, it is better to contact a service center.

How much does it cost replacing the thermostat at a service center?

The cost depends on the refrigerator model and region:

• 🔧 Replacement of thermostats in mechanical refrigerators (Atlant, Biryusa) — 1500-2500 rubles (with spare parts).
• 🔧 Replacement in electronic models (Samsung, LG) — 2500-4000 rubles (board flashing may be required).
• 🔧 In premium refrigerators (Liebherr, Bosch) — from 4000 rubles.

If you buy a spare part yourself, the work of a technician will cost 1000-1500 rubles.

Is it possible to do without a thermal relay by closing the contacts directly?

Technically yes, but this is a temporary solutionwhich leads to:

• ⚡ Increased energy consumption (the compressor will work without stopping).
• ❄️ Freezing of the evaporator and the back wall of the refrigerator.
• 🔥 Overheating of the compressor and the risk of its breakdown.

Such “repairs” are justified only in two cases:

1. You are waiting for the delivery of a new thermostat and you need to temporarily store food.
2. The refrigerator is used in a non-residential area (garage, cottage), and the temperature inside not critical.

🔧 How to close the contacts:

Turn off the refrigerator, remove the terminals from the thermostat and connect the wires 3 and 4 (usually red and brown) to each other using a twist or terminal block. Turn on the refrigerator - the compressor should start.

Why did the new thermal relay quickly break down?

If the replaced thermal relay fails within a month, the reasons may be the following:

• 🔌 Incorrect connection of wires —phase and zero are reversed, or poor contact at the terminals.
• 🧊 Freon leak —the compressor wears out, which leads to overheating and tripping of the protection.
• 🔥 Compressor malfunction —if the motor “pulls” too much current, the thermal relay may burn out.
• 🔧 Defective spare parts —especially important for cheap thermal relays with AliExpress.
• 📉 Incorrect calibration —if the capillary tube does not fit well to the evaporator, the relay operates in extreme conditions.

🔍 What to do:

1. Check the integrity of the compressor windings (the resistance between the terminals should be within 20-50 Ohm).
2. Make sure that the capillary tube fits tightly to the evaporator and is not pinched.
3. Check the purchased thermostat with a multimeter before installation.