How the temperature regulator works in the refrigerator: device, setup and repair

A refrigerator is one of the most important household appliances, the correct operation of which determines the safety of food and comfort in the home. The central element of its control system is temperature controllerresponsible for maintaining an optimal microclimate inside the chambers. But how exactly does it function? Why does the refrigerator sometimes begin to be “capricious”—it freezes too much, and then, on the contrary, it doesn’t cool well? And is it possible to independently diagnose problems with the thermostat?

In this article we will figure out how the temperature controller works in different types of refrigerators (mechanical, electronic, inverter), what signals indicate its malfunction, and what to do if the thermostat fails. You will also learn how to correctly set the temperature depending on the model (Indesit, Samsung, Atlant, Liebherr etc.) and the load on the chambers. The material will be useful for both beginners and those who have already dealt with repairing equipment.

Temperature controller design: mechanics vs electronics

The temperature controller (or thermostat) is a sensor that controls the level of cooling in the refrigerator and freezer compartments. Its main task is to turn the compressor on and off depending on the temperature readings. There are two main types of regulators:

• 🔧 Mechanical - use a capillary tube with refrigerant (freon), which responds to temperature changes. When heated, the pressure in the tube increases, which closes the contacts and starts the compressor.
• 📱 Electronic —equipped with thermistors (semiconductor sensors) that send signals to the control board. Such systems are more accurate and allow flexible adjustment of modes.

Modern models (for example, Samsung RB30A3200SA or LG GB-B459SLQZ) are often used inverter compressors, which operate without sudden switching on/off, and smoothly regulate power. In this case, the thermostat is integrated into the control system and can have up to 5-7 sensors in different zones of the refrigerator.

Mechanical regulators are easier to repair, but less accurate. They can be found in budget models (Biryusa, Atlant MXM-1708) or refrigerators older than 10 years. Electronic ones require diagnostics using a multimeter and are often replaced entirely if they break down.

Signs of a malfunctioning thermostat

If the temperature regulator does not work correctly, this immediately affects the functioning of the entire refrigerator. Here are the key “symptoms” that should alert you:

• ❄️ The compressor is constantly running without stopping - indicates the thermostat contacts are closed in the “on” position.
• 🔥 The refrigerator does not cool, but the light inside is on - an open circuit or sensor failure is possible.
• 🌡️ Sudden temperature changes - it is either too cold or warm, which is typical for wear of the mechanical thermostat.
• 💡 An error flashes on the display (for example, E1, H1 y Beko or OF at Indesit) - a signal about a sensor malfunction.

Critical point: if a refrigerator with a mechanical thermostat suddenly stops turning on, and clicks are heard when you turn the control knob - this almost always means breakdown of the contact group. In 80% of cases, the thermostat needs to be replaced.

Electronic models are characterized by other problems - for example, control board firmware failure or oxidation of sensor contacts. In this case, a reboot (disconnect from the network for 10–15 minutes) or flashing the firmware through the service mode can help.

⚠️ Attention: If the refrigerator is connected to the network through a voltage stabilizer, first check its functionality. Voltage surges are a common cause of false thermostat alarms.

How to check the thermostat yourself

Diagnostics can be carried out without calling a technician if you follow the step-by-step instructions. For mechanical thermostats you will need a multimeter, for electronic ones - access to the service menu (instructions for popular models are given below).

Remove the protective casing from the regulator (usually secured with latches or screws)

Disconnect the wires from the terminals (take a photo of their location!)

Translate thermostat knob to the “Max” or “7” position

Ring the contacts with a multimeter in resistance mode (should be 0 Ohm)

Turn the knob to the "Off" position - the resistance should become infinite-->

For electronic thermostats, the algorithm is different:

1. Disconnect the refrigerator from the mains.
2. Remove the back cover (in some models Samsung or LG sensors are located inside the chamber behind the plastic panel).
3. Check the thermistor resistance at room temperature (usually 5–10 kOhm). If the readings are “0” or “∞”, the sensor is faulty.
4. For accurate diagnostics, connect the refrigerator and enter service mode (button combinations depend on the model).

For example, for refrigerators Indesit the service menu is activated by holding the buttons Super Cool + Holiday for 5 seconds. In the menu you can see error codes and current sensor readings.

Table: Optimal temperatures for different zones of the refrigerator

Incorrect thermostat settings can lead to food spoilage or increased energy consumption. Here are the recommended values for the main zones:

For refrigerators with a system No Frost the temperature mode is set automatically, but it can be adjusted manually. For example, models Liebherr CNef 4315 have separate controls for the refrigerator and freezer compartments in increments of 1°C.

⚠️ Attention: If ice appears on the walls of a refrigerator, this may indicate not only a malfunction of the thermostat, but also a clogged drainage system or a failure of the fan. Also check the rubber seals on the doors. No Frost Ice appears on the walls; this may indicate not only a thermostat malfunction, but also a clogged drainage system or a fan failure. Also check the rubber seals on the doors.

How to adjust the temperature in refrigerators of different brands

There are no universal instructions - each brand uses its own control algorithms. Let's look at the configuration features for popular manufacturers:

• 🔄 Samsung (RB, RS, RT series):

  Use touch controls or mechanical handles. In models with a display (Samsung RB37J5230SS), the temperature is adjusted using the Fridge and Freezer buttons in steps of 1°C. To reset settings, hold Power Cool 10 seconds.

• ⚙️ Indesit (C series, TIA, BIAA):

  Mechanical controls with positions from 1 (warmest) to 5 (coldest). In refrigerators with No Frost (Indesit DF 4180 Wa mode has been added Holiday to save energy during prolonged absence.

• ❄️ Atlant (models MXM, HM):

  Classic mechanical thermostats. In the freezer compartment, the handle has 7 positions, in the refrigerator - 5. For models with Low Frost (Atlant MXM-2835-90, it is recommended to set the average value (3-4) for uniform cooling.

• 📲 Liebherr (CN, SBS series):

  Electronic control with the ability to separately configure zones. In models with BioFresh (Liebherr SBSes 7255), the temperature in the vegetable drawers is maintained at 0°C automatically.