A modern refrigerator is a complex unit where each element is responsible for the safety of your products. If you notice that the equipment has begun to work incorrectly, for example, it freezes food or, conversely, does not cool well, the first thought is often to check the temperature control system. Temperature sensor is a key link in this chain, transmitting information about the microclimate inside the chambers to the electronic module or mechanical thermostat.
Finding this element can be a difficult task for an unprepared user, since manufacturers often hide it in hard-to-reach places to avoid accidental damage. The location of the sensor directly depends on the design of your model: be it the good old Atlant or high-tech Samsung No Frost. In this article, we will analyze in detail where exactly to look for this component and how to understand that the problem lies precisely there.
Understanding where it is thermocouplewill help you not only with self-diagnosis, but also when communicating with a technician, which will save time and money.
Before you begin disassembling, you need to understand the types of sensors that are used in refrigeration technology. In older models and simple units, a mechanical one is often found, which is a sealed capsule with gas or liquid connected to a control knob by a long capillary tube. Modern devices are dominated by electronic thermostat, which is a sealed capsule of gas or liquid connected to a control knob by a long capillary tube. Modern devices are dominated by electronic NTC thermistors -compact elements that change their resistance depending on the ambient temperature.
Electronic sensors usually look like a small plastic tip at the end of a wire, often enclosed in metal or plastic sleeve. They are characterized by high accuracy and response speed, which allows the system No Frost to effectively manage defrost cycles. Mechanical analogues are more inert, but are considered reliable and less susceptible to power surges in the network.
⚠️ Attention: If you try to replace a mechanical thermostat with an electronic one (or vice versa) without reflashing the control module, the refrigerator will not work. These systems are not directly compatible!
The number of sensors in the unit can vary from one to several. In simple models, the sensor controls the temperature only in the refrigerator compartment. In complex systems Multi-Flow or Twin Cooling individual thermistors can monitor the climate in the freezer, in the freshness zone, and even control the evaporator temperature to control defrost.
In classic refrigerators with a drip defrosting system, the search for a sensor (or thermostat) usually begins with an inspection of the refrigerator compartment. Most often temperature regulator and the sensitive element is located inside the main compartment. If you have a model with mechanical control, you will see a knob with numbers, and the sensor itself will be hidden behind a plastic panel or built into the case.
In units with electronic control, the sensor is often hidden under a decorative trim on the ceiling of the chamber or in one of the side walls. To get to it, you may need to carefully remove the lighting cover or the protective cover of the air duct. Thermistor in such models it can be integrated into the general wiring harness going to the control board.
Sometimes manufacturers hide the sensor in a special pocket on the back wall of the camera, which looks like a small thickening of plastic. This is done to ensure that the sensor does not come into direct contact with the products and is not damaged when they are moved. To access it, in some cases it is necessary to dismantle the entire back panel of the refrigerator compartment.
Searching in the refrigerator compartment is only the first stage. If a visual inspection does not produce results, you should pay attention to the design of the evaporator, which in models No Frost is located behind the rear wall of the freezer. This is where the answer to cooling problems often lies.
In refrigerators with a system No Frost (without frost), the arrangement of sensors is more complex and numerous. It is critically important here defrost sensor, which monitors the temperature of the evaporator in order to turn on the heating element in time and melt the ice. It is located directly on the fins of the evaporator, often in the lower or middle part, and can be secured with a clamp or inserted into a special hole.
In addition, the main one can be located in the freezer compartment air temperature sensor. In two-compartment models, it usually hangs on the back wall or is built into the ceiling of the freezer. Its task is to inform the module when it is necessary to stop the compressor having reached the specified minus values. In some models LG or Whirlpool this element can be hidden inside the plastic fan casing.
Access to sensors in the zone No Frost requires complete defrosting of the refrigerator within 12-24 hours. Trying to remove the back panel while there is ice there will lead to damage to the plastic air ducts and aluminum evaporator tubes. The most common mistake is trying to pick out the ice with a knife, which guarantees a breakdown of the freon circuit and expensive repairs.
☑️ Preparing to disassemble the freezer
The freshness zones (zero chambers), which are found in many modern models, deserve special attention. The temperature in these compartments is maintained at about 0°C, and this process is monitored by its own thermal sensor. It is usually located at the top of this specialized box or on the partition separating the freshness zone from the main chamber.
In some premium models, for example, from Bosch or Siemens, sensors can be built directly into the walls of the drawers or into the system air circulation, which makes them virtually invisible without completely disassembling the interior. If your refrigerator no longer supports the “zero zone” mode, the problem may lie in this local sensor.
There are several signs that indicate a malfunction thermostat or thermistor. The most obvious is the continuous operation of the compressor without shutdowns, which leads to the formation of a “coat” of ice in the refrigerator compartment and freezing of food. In this case, the sensor simply does not give a signal to the module that the required temperature has already been reached.
The opposite situation - the refrigerator does not turn on at all or operates in very short cycles, not having time to cool the chamber to the required values. This may mean that sensor is "lying", telling the system that it is already too cold inside. In such cases, the products begin to deteriorate, and an unpleasant odor may appear in the chamber.
An error on the electronic display may also indicate a malfunction. Many modern models can self-diagnose and display error codes, which are explained in the instructions. For example, a code associated with an open circuit in the sensor will immediately indicate a problem in the electrical circuit of the sensor.
⚠️ Attention: If the refrigerator makes loud clicks when trying to start, but the compressor does not start, it may not be the sensor, but the start relay or the motor itself. Do not rush to change all the parts at once without accurate diagnostics with a multimeter.
How to check the sensor with a multimeter?
To check, remove the sensor and connect the multimeter probes to it in the resistance (Ohm) measurement mode. At room temperature, a working NTC thermistor should show a certain resistance (usually from 2 to 10 kOhm, depending on the model). If the multimeter shows infinity (open) or zero (short circuit), the sensor is faulty. You can also hold the sensor in your hand: the resistance should begin to change (mouth) as it heats up.
For a deeper understanding of the differences between the types of sensors and their locations, check out the table below. It will help systematize information and quickly identify a node in your model.
| Sensor type | Location | Principle of operation | Frequent symptoms of failure |
|---|---|---|---|
| Mechanical thermostat | Inside the chamber (handle) or outside the housing | Gas expansion in the capillary opens the contacts | The refrigerator does not turn off or turn on |
| NTC thermistor (air) | On the wall or ceiling of the chamber | Change in resistance when the temperature changes | Incorrect temperature, errors on the display |
| Defrost sensor | On the evaporator (behind the rear wall) | Temperature control of the defrost heater | Ice accumulation ("coat") in the freezer |
| Defrost sensor (defrost) | At the bottom of the evaporator | Turns off the heating element when a certain temperature is reached | Overheating of the evaporator, burning smell, water leakage |
If you determine that temperature sensor really failed, it must be replaced. The replacement process depends on the design, but the general algorithm is similar for most models. First you need to purchase a compatible part: for electronic sensors, matching resistance is important (for example, 5 kOhm, 10 kOhm or 50 kOhm at 25°C), since there are no universal solutions here.
After purchasing and defrosting the refrigerator, remove the faulty element. Often it is simply inserted into a groove or secured with a plastic clamp. The new sensor is installed in the same place. It is important to ensure tight contact with the surface that it must control; sometimes special thermal paste is used for this (although in household refrigerators this is rarely done, relying on the tightness of the fit).
After installation, reassemble all panels in the reverse order and turn on the refrigerator. The first full freeze can take up to 24 hours. At this time, do not completely load the chamber with products, let the unit gain temperature and stabilize operation.
Owners of complex two-compressor models or units with a system Full No Frost should be especially careful during assembly. An incorrectly installed back panel can interfere with air circulation, which will lead to rapid fouling of ice on the evaporator even with a working sensor.
Sometimes the cause of the malfunction is not the sensor itself, but oxidized contacts in the connector or a frayed wire. Carefully inspect the wiring harness leading from the sensor to the control board. If the wires are intact, and the resistance of the sensor changes when heating/cooling, the problem may be deeper - in the control module.
Is it possible to temporarily short-circuit the sensor to make the refrigerator work?
Technically, short-circuiting some types of sensors (or installing a resistor with a certain value) can force the refrigerator to operate in emergency mode. However, this is dangerous: the system will no longer control the temperature, which will lead either to defrosting of the food or to freezing of the evaporator and breakdown of the compressor. This can only be done for short-term diagnostics.
Why doesn’t the new sensor solve the problem?
If the replacement thermistor did not help, there may be several reasons: the resistance of the new part is incorrectly selected, there is a problem in the control board (the resistor in the sensor circuit has burned out), the defrost heating element is faulty, or there is a freon leak. It is also possible that the sensor is working, but is installed incorrectly and is not in contact with the surface of the evaporator.
How often should the temperature sensor be changed?
The service life of sensors is usually 5-10 years or more. They are not consumables and are replaced only when they break down. However, under conditions of constant power surges in the network, their resource may be reduced.
Does the location of products affect the operation of the sensor?
Yes, if you tightly pack the refrigerator so that the products block the air flow or come into direct contact with the sensor, the temperature readings will be distorted. This may lead to incorrect operation of the compressor. Always leave space for air circulation.