Modern brand refrigerators Liebherr are famous for their accuracy in maintaining the climate inside the chambers, which directly affects the safety of food. A complex system of sensors is responsible for this accuracy, which at any time reads data on the thermal background and transmits it to the control board. Understanding exactly where these elements are located is necessary to carry out proper diagnostics, especially if the unit has stopped freezing or has started to freeze excessively.
Owners are often faced with a situation where an alarm light comes on on the display, and the compressor idles or, conversely, does not turn off at all. In most cases, the reason lies in the failure of one of the thermistors or a violation of its contact. Temperature sensors - these are consumable elements whose resistance changes depending on the heat, and over time they can fail.
Knowing the exact location of the sensors allows you to reduce repair time and avoid unnecessary dismantling of panels. In this article we will analyze in detail the architecture of the thermoregulation system in various models Liebherrincluding systems SmartSteel and classic versions with mechanical control. You will learn how to get to hidden elements without damaging the interior of the refrigerator compartment.
The principle of operation of the Liebherr thermoregulation system
The cooling system in refrigerators Liebherr is built on constant monitoring of temperature indicators in different zones. The main element here is an NTC thermistor, the resistance of which drops as the temperature rises. The control board reads these changes and decides to turn on or off the compressor, fans and valves.
Unlike older models with mechanical thermostats, where the sensor is often combined with a switch, in modern systems electronic control is divided into independent circuits. This means that separate sensors are responsible for the temperature in the refrigerator compartment, freezer compartment and freshness zone. If one of them fails, the system goes into emergency mode or stops correctly controlling a specific evaporator.
⚠️ Attention: Do not try to check the operation of the sensors while the refrigerator is connected to the mains. A short circuit can damage the main control board, the cost of which is significantly higher than the cost of the sensor itself.
The accuracy of the readings depends not only on the serviceability of the element itself, but also on the quality of its contact with the air or the surface of the evaporator. Some models Liebherr use air sensors hanging in a free flow, while others use contact sensors mounted on tubes. It is impossible to confuse them when replacing them, since they have different resistance characteristics.
Sensors in the refrigerator compartment: search and access
The search for a sensor in the main chamber usually starts from the back wall. In most models Liebherr the air temperature sensor is located at the top of the rear panel, often hidden behind a decorative trim or plastic casing. You can get to it by carefully unclipping the fasteners or removing the shelf, if the design requires it.
In models with the system NoFrost or DuoCooling the situation may be more complicated. There may be an additional evaporator defrost sensor, which is located behind the rear panel, hidden by a layer of polyurethane foam or a plastic screen. To access it, partial disassembly of the internal volume of the chamber is often required.
- 🔍 Upper sensor: Usually located under the ceiling of the chamber or in the upper corner of the rear wall, it is responsible for the overall air temperature.
- 🌡️ Bottom sensor: Found in two-compressor models, located in the lower third of the rear wall to control the gradient temperatures.
- ❄️ Defrost sensor: Located directly on the evaporator, often hidden behind the back wall, controls defrosting.
If your model is equipped with a zone BioFresh, then inside the drawers or additional sensors may be located underneath them to maintain zero temperature. Their location varies from model to model, but most often they are built into the design of the guides or the bottom of the drawer. Replacement such elements require the complete removal of containers for vegetables and fruits.
When dismantling the back wall, be extremely careful with the plastic latches. The material in old refrigerators Liebherr can be brittle due to constant exposure to low temperatures. A sudden movement can lead to breakage of fasteners, which will require additional costs for restoration.
Location of sensors in the freezer compartment
The freezer compartment in refrigerators Liebherr has its own independent control system, especially when it comes to two-compressor models. The main sensor here is most often built into the front panel of the evaporator or located in the air duct through which cold air is forced into the chamber. In systems NoFrost access to it is usually blocked by a plastic grill or fan cover.
To access the insides of the freezer, it is often necessary to completely defrost the unit within 12-24 hours. This is necessary not only for safety, but also to ensure that ice does not interfere with the removal of the panels. An attempt to remove a cover with ice frozen inside is guaranteed to lead to breakage of the plastic or damage to the evaporator tubes.
| Sensor type | Location | Function |
|---|---|---|
| Air NTC | Upper part of the chamber, near the fan | General temperature control |
| Contact NTC | On the evaporator pipes | Defrost cycle control |
| Protective thermostat | Next to the defrost heating element | Emergency heating shutdown |
The defrost sensor in the freezer deserves special attention. It is critical for the operation of the system NoFrost. If it shows incorrect data, the refrigerator may not start defrosting, which will lead to fouling of the evaporator and the cessation of air circulation. Visually, this element often looks like a small metal or plastic cylinder pressed to the tube with a clamp.
Hidden sensors in the BioFresh zone and zero zone
Technology BioFresh is the hallmark of the brand Liebherr, providing ideal conditions for storing meat, fish and vegetables. To maintain such precise parameters (close to 0°C), a separate cooling circuit and, accordingly, its own temperature sensors are used. They are often hidden from the user's eyes and are located in the technical compartment behind the back wall of the chamber or under the bottom of the drawers.
In some advanced models, the sensors are built directly into the drawer lid BioFresh or into its side walls. This allows you to read the temperature not just of the air in the chamber, but directly inside the container with the products. This design requires caution when removing the boxes: a sharp jerk can damage the thin wires going to the sensor.
Diagnostics of these elements is complicated by the fact that they are often covered with decorative panels made of glass or metal. To get to the mounting location, you may need to remove the entire internal lining of the freshness zone. Resistance such sensors may differ from standard ones, so when replacing it is important to select original spare parts or exact analogues with identical characteristics.
⚠️ Attention: In models with electronic control of the BioFresh zone, disconnecting the sensor may cause blocking the operation of the entire refrigerator compartment. The system will regard this as a critical malfunction.
If you notice what is in the boxes BioFresh food freezes or, conversely, spoils faster than usual, it is worth checking this particular circuit first. The error may lie not only in the sensor itself, but also in the oxidation of the contacts where the wire passes through the drawer hinges, where constant movement occurs.
Why do BioFresh sensors fail more often than others?
They are exposed to a more aggressive environment due to high humidity and frequent contact with condensation that forms when opening drawers. Additionally, mechanical stress when loading products also plays a role.
Fault diagnosis: multimeter and error codes
Before you start disassembling the refrigerator, you need to make sure that the problem is really in the sensor. Modern refrigerators Liebherr equipped with a developed self-diagnosis system. If the sensor fails, the corresponding error code or flashing indicator lights up on the display. For example, "F" series codes often indicate a faulty sensor.
For an accurate test, you will need a digital multimeter switched to resistance (Ohms) measurement mode. The sensor is removed from the mounting location and its resistance is measured at room temperature. Normal values are usually in the range from 2 to 10 kOhm, but the exact numbers depend on the specific model and type of sensor.
- 📉 Checking for open circuit: If the multimeter shows one or infinity, the circuit is open, the sensor is faulty.
- 📈 Checking for a short circuit: If the resistance is close to zero, the sensor is broken and requires replacement.
- 🌡️ Heat test: Hold the sensor in your hand - the resistance should gradually decrease. If the number does not change, the element does not work.
It is also important to check the integrity of the wiring going from the sensor to the control board. Often the wires fray where the door hinges bend or pass through the doorway. In such cases, replacing the sensor itself will not work, since the signal simply does not reach the “brain” of the refrigerator.
☑️ Algorithm for checking the sensor
Replacing and calibrating temperature sensors
The process of replacing the sensor in refrigerators Liebherr requires not only technical skills, but also cleanliness. After dismantling the old element, the installation site must be cleaned of dirt and old lubricant residues. The new sensor is installed in the same position as the old one, using the original fasteners.
Particular attention should be paid to the sealant. If the sensor is contact (inserted into a tube), the wire entry point is often sealed with a special compound to prevent moisture and refrigerant from entering. Using the wrong sealant may cause it to crack at low temperatures.
After installing and connecting the new element, the refrigerator must be turned on. Some models require resetting the error through the menu or a long disconnection from the network (about 15-20 minutes) to reboot the controller. The system should take new readings and exit the emergency mode.
⚠️ Attention: Do not use ordinary electrical tape to insulate the contacts. In refrigeration conditions, the glue loses its properties, and the tape itself becomes tanned. Use only heat shrink or special refrigeration insulation.
If the problem does not disappear after replacement, it may not be the sensor itself, but the control board that is not reading the signal correctly. In this case, a more in-depth diagnosis of the electronics is required, which is best entrusted to the service center specialists.
Is it possible to use a universal sensor?
Technically, you can select an analogue with a similar resistance, but the resistance change curve at different temperatures may differ. This will lead to the refrigerator working incorrectly (not freezing or over-freezing).
Frequently asked questions (FAQ)
How to understand that the temperature sensor in Liebherr is faulty without disassembling?
Pay attention to the behavior of the refrigerator: if it works non-stop, it does not rises in temperature or, conversely, turns food into ice, this is a sign of a malfunction. Also, error codes starting with the letter F (for example, F1, F2) may appear on the display, which indicate a specific faulty circuit.
Where is the main sensor located in models with a single compressor?
In single-circuit models, the main sensor is most often located in the upper part of the refrigeration chamber, since cold air falls down. However, in systems DuoCooling there may be two of them: one in the refrigerator compartment, the other in the freezer compartment, and they do not depend on each other.
Why does the refrigerator not turn on after replacing the sensor?
Perhaps the protection system is blocking the start due to incorrect readings (if the sensor is of the wrong type) or the error code has not been reset. Try turning off the power to the unit completely for 30 minutes. If this does not help, check that the wires are connected correctly.
Is it possible to temporarily short-circuit the sensor to make the refrigerator work?
Theoretically, this will make the refrigerator think that the temperature is very low, and it will stop turning on, or vice versa - it will work constantly, which will lead to freezing and breakdown of the compressor. It is strictly not recommended to do this, even as a temporary measure.