The thermostat (or thermostat) is the “brain” of the refrigerator, which controls the temperature in the chambers and controls the operation of the compressor. When it fails, the equipment either stops freezing or works non-stop, building up an ice “coat” and burning electricity. According to statistics from service centers, up to 30% of calls concerns about “non-freezing” refrigerators are associated precisely with a malfunction of the thermostat - and in half of the cases you can repair or replace it yourself, saving on calling a technician.
In this article you will find step-by-step instructions with videohow to check the thermostat in refrigerators of different brands (Indesit, Atlant, Samsung, Beko etc.), without having repair experience. We will analyze:
- 🔍 5 signsthat the problem is in the thermostat, and not in the compressor or seal
- 🛠️ Checking methods - with and without a multimeter (including “folk” methods with boiling water)
- 📹 Video instructions for mechanical and electronic thermostats
- ⚡ Typical errorsdue to which diagnostics give false results
All methods have been tested on real refrigerators and are suitable for models with mechanical control (twist handle) and electronic (touch buttons). If your refrigerator is equipped with a No Frostsystem, pay attention to special section —there are nuances there.
5 signs faulty thermostat: when is it time to check
Before disassembling the refrigerator, make sure that the problem is really in the thermostat. Here key symptomswhich 90% indicate its breakdown:
- ❄️ The compressor does not turns on - the refrigerator is “silent”, the light inside is on, but the motor does not start even after manually turning the thermostat knob to maximum.
- ⚡ The motor runs without stopping —the compressor hums constantly, does not turn off for “rest”, and a thick layer of ice forms in the freezer.
- 🌡️ The temperature does not correspond to the settings —in the refrigerator compartment +10°C when set to +4°C, or vice versa, the food freezes.
- 🔄 Spontaneous shutdown —the refrigerator suddenly turns off and turns on only after unplugging the plug from the socket.
- 💥 Clicks without starting the motor —the characteristic clicks relay is heard, but the compressor does not starts.
If at least one of these signs matches, the probability of a thermostat malfunction is high. However rule out simple causes first:
- 🔌 Check whether the door is tightly closed and whether the seal is torn.
- ⚡ Make sure that the voltage in the network is stable (not lower than 200V).
- ❄️ Defrost the refrigerator - sometimes ice build-ups block the sensors.
Where the thermostat is located: diagrams for different models
The location of the thermostat depends on brand and control type the refrigerator. In 90% of cases, it is hidden behind a plastic panel inside the refrigerator compartment, but there are exceptions.
| Refrigerator brand | Control type | Where to look thermostat | Photo/diagram |
|---|---|---|---|
| Atlant, Indesit, Ariston | Mechanical (handle) | Under the top shelf of the refrigerator compartment, behind the plastic cover. 2-3 wires and a capillary tube are suitable for it. | 📷 [Diagram 1] |
| Samsung, LG (with display) | Electronic | Inside the top panel (above the door) or behind the back wall. Often combined with a control module. | 📷 [Diagram 2] |
| Beko, Vestfrost | Mechanical | On the right inside the chamber, behind the decorative trim. Can be hidden under the egg tray. | 📷 [Diagram 3] |
| Stinol, Nord | Mechanical/electronic | In the upper corner of the refrigerator compartment or behind the front panel (under the temperature control knob). | 📷 [Diagram 4] |
In refrigerators with a No Frost thermostat system, the thermostat is often duplicated defrost sensor (defroster). If your model is equipped with such a system, check both elements.
How to distinguish a thermostat from a No Frost sensor?
The thermostat always has:
- 🔌 Connection to the compressor (thick wires)
- 🧊 Capillary tube (thin copper tube going into the chamber)
- 🔄 Mechanical handle or electronic control buttons
The No Frost sensor looks like a small plastic cylinder with two wires and is attached to the evaporator.
What you will need to check: tools and preparation
You do not need professional instruments to diagnose the thermostat. Here is the minimum set:
- 🔧 A Phillips/flat head screwdriver for removing the protective panel.
- 📱 Multimeter (or tester) - for checking the contacts. Even the cheapest model for 300₽ will do.
- 🧊 Thermometer (household, up to -30°C) - for the "boiling water" test (if there is no multimeter).
- 🔌 Insulating tape/terminals - for temporary connection wires.
- 📝 Phone camera —to photograph the connection diagram before disconnecting the wires.
If you don’t have a multimeter, you can get by by dialing using light bulbs and batteries (method described below). For models with electronic control (Samsung, LG), you may additionally need soldering iron to check the board tracks.
Disconnect the refrigerator from the mains|Take a photo of the location wires|Prepare tools|Get access to the thermostat (remove shelves if necessary)|Check the voltage in the outlet (should be 220-230V)-->
⚠️ Attention: Before starting work be sure to defrost the refrigerator and wipe all surfaces dry. Humidity can distort the multimeter readings or cause a short circuit when dialing.
Method 1: Checking the thermostat with a multimeter (step by step with video)
This is the most reliable diagnostic method. Suitable for all mechanical thermostats (for example, models K59, K56, TAM-133, Danfoss 077B6). Video instructions at the end of the section.
Step 1. Remove the thermostat:
- Unplug the refrigerator.
- Remove protective plastic panel (usually attached with latches or 1-2 screws).
- Carefully disconnect the wires from the thermostat, first photographing their location. On most models, the wires are connected to terminals 3 and 4 (or 6 and 4 for thermostats with three terminals).
- Unscrew the nut securing the capillary tube and remove the thermostat.
Step 2. Check the contact resistance:
- Switch the multimeter to mode
continuity(or resistance measurement, 200 Ohms). - Connect the probes to the terminals
3 and 4(see diagram below). - At room temperature (+20°C) the contacts should be closed (resistance ~0 Ohm).
- Immerse capillary tube thermostat in a container with ice water (0°C). The contacts should open (resistance → ∞).
- Heat the tube in hot water (+50°C). The contacts will close again.
Step 3. Check the circuit for open circuit:
- Switch the multimeter to mode
200 kOhm. - Connect the probes to terminals
3 and 6(if any). The resistance should be between 1-10 kOhm. - If there is no sign of resistance (∞), the thermostat is faulty.
📹 Video instructions: [Insert video from YouTube, for example: “Checking the refrigerator thermostat multimeter"]
Method 2: How to check the thermostat without a multimeter (3 methods)
If you don’t have a tester at hand, use alternative methods. They are less accurate, but will help confirm the diagnosis.
Method 1: Direct connection of the compressor
Disconnect the wires from the thermostat and connect them directly (simulating closed contacts). If the compressor starts, the problem is in the thermostat.
⚠️ Attention: Do not leave the compressor on for more than 5 minutes without a thermostat! This can lead to motor overheating.
Method 2: Test with boiling water
This method is suitable for thermostats with capillary tube:
- Immerse the end of the tube in boiling water (+90°C).
- If the thermostat is working, after 1-2 minutes you will hear click the contacts have opened.
- Take out the tube and cool it under running cold water. A second click should sound (closed).
Method 3: Check with a light bulb
Assemble a simple circuit:
- 💡 Connect to the thermostat terminals 220V light bulb via a battery (or power supply 3-12V).
- 🔥 Heat the capillary tube with a lighter. The light bulb should go out (open circuit).
- ❄️ Cool the tube - the light bulb will light up again.
Features of checking the thermostat in No Frost refrigerators
In systems No Frost the thermostat works in tandem with defrost sensor i timer. If the refrigerator does not freeze, the problem may be in any of these elements. Here's how to distinguish them:
| Symptom | Probable cause | How to check |
|---|---|---|
| The compressor does not turn on, the fan does not work | The thermostat or control module is faulty | Test the thermostat with a multimeter (terminals 3-4). Check the power supply to the module. |
| The refrigerator is freezing, but there is ice in the freezer | The defrost sensor or heating element is broken | Check the resistance of the sensor (should be 1-10 kOhm). The heating element rings for a break. |
| The fan works, but the compressor does not | Open circuit of the thermostat or compressor relay | Ring the circuit from the thermostat to the compressor. Check the relay (shake it - if it rattles, it’s faulty). |
In refrigerators No Frost the thermostat is often built into the electronic module. If the multimeter shows a malfunction and replacing the thermostat does not help, the problem may be in control board.
4 errors when checking the thermostat (and how to avoid them)
Even experienced craftsmen sometimes make mistakes that lead to k false conclusions. Here are the most common:
- 🔌 Check under voltage —never dial the thermostat without unplugging the refrigerator from the power supply! This may result in electric shock or burning of the multimeter.
- 🧊 Ignoring the capillary tube - if it is damaged or pinched, the thermostat will not work correctly even with good contacts.
- 📉 Not taking into account the temperature - contacts thermostats should be checked at room temperature (+20°C). In cold or hot weather, the results will be incorrect.
- 🔄 Confusion with terminals - before disconnecting the wires be sure to take photographs their location. Incorrect connection can burn the compressor.
Another typical mistake is checking the thermostat separately from the capillary tube. These two elements work together: if the tube has lost its tightness or is filled with the wrong gas, the thermostat will malfunction even with good contacts.
FAQ: Frequently asked questions about checking the thermostat
Can it be repaired thermostat or just replacement?
Mechanical thermostats cannot be repaired —they are only replaced. In electronic models, it is sometimes possible to restore the board tracks or replace the sensor, but this requires soldering work.
How much does a new thermostat cost?
The price depends on the model:
- 💰 For Atlant/Indesit: 800–1500₽ (for example, TAM-133 or K59).
- 💰 For Samsung/LG (electronic): 1500–3500₽.
- 💰 Universal (for example, Danfoss 077B6): 1200–2000₽.
Before purchasing, check part number (written on the thermostat body).
How check the thermostat in a two-chamber refrigerator?
In two-chamber refrigerators (Samsung RL-33, Atlant. MXM-170) there are often two thermostats separate for the refrigeration and freezer compartments. Check them in turn:
- Turn off the power.
- Find the thermostat of the problem chamber (usually it is closer to it).
- Test the contacts with a multimeter (as described above).
If both are faulty, both need to be changed - they are calibrated to work together.
What to do if the thermostat is working, but the refrigerator does not work?
Check other elements:
- 🔌 Compressor — ring the windings (the resistance between the terminals should be 20-40 Ohms).
- ⚡ Start relay —shake: if it rattles, it is broken.
- 🧊 Temperature sensor (in electronic models) - resistance should change when heating/cooling.
- 🔋 Control board —inspect for burnt elements.
Is it possible to temporarily operate a refrigerator without a thermostat?
🚨 Absolutely not! Without a thermostat, the compressor will work continuously, which will lead to:
- 💥 Overheating and engine combustion.
- ⚡ Increased energy consumption (up to 500-700 kW/month!).
- ❄️ Icing of the evaporator and spoilage of food.
If the thermostat is broken, turn off the refrigerator before replacing the part.