A failure in the operation of a refrigeration unit often takes you by surprise, especially when food begins to deteriorate and the inside of the chamber becomes warmer than expected. The first step to restoring the functionality of household appliances is to find the cause of the malfunction, and very often the culprit of the problem is thermal relay. This small but critical component is responsible for cycling the compressor on and off, maintaining the set temperature.
The location of this element may vary depending on the model, manufacturer and year of manufacture of your equipment. In some cases, you can get to it by simply removing the back cover, in others, you will need to partially disassemble the interior of the refrigerator or freezer. Understanding how where exactly to look for a part will save you time and nerves when diagnosing.
In this article we will analyze in detail the architecture of modern refrigerators, indicate the exact locations of installation of temperature sensors and regulators in different types of structures. You will learn how to safely remove the element for inspection and what to look for during a visual inspection to avoid mistakes that can lead to more serious damage.
Types of temperature sensors and their purposes
Before you go looking, it is important to understand what exactly you are looking for, since different cooling systems use different types of temperature control devices. In older models of refrigerators, such as classic Atlant or Biryusa, a mechanical thermostat is most often found. This device is a block with a capillary tube that responds to changes in gas pressure inside the tube when the temperature changes.
Modern units with a system No Frost and electronic control are equipped with thermistors. These are small electronic components whose resistance changes depending on the ambient temperature. They are usually compact in size and connected to the main control board via connectors, which makes finding and replacing them somewhat easier, but requires a multimeter for accurate diagnosis.
⚠️ Attention: Do not try to replace a mechanical thermostat with an electronic thermistor or vice versa. These devices have fundamentally different operating schemes and are not interchangeable without serious alteration of the electrical circuit of the refrigerator.It is also worth mentioning the existence of defrost timers and thermal compressor protection relays, which are often confused with the main thermal relay. The thermal relay is usually installed directly on the compressor housing and protects the engine from overheating, while the thermal relay (thermostat) controls the temperature inside the chambers. Confusion in these concepts can lead to the purchase of unnecessary spare parts.
📊 What type of refrigerator control do you have?Mechanical handleElectronic displayI don’t know / I’ll look at the instructionsI have an old Soviet refrigeratorLocation of the thermostat in single-chamber refrigerators
In classic single-chamber models, where the freezer compartment is a small compartment inside the main chamber, the thermostat is most often hidden from the user's eyes. Manufacturers strive to minimize visual noise, so they hide mechanical units behind decorative panels. The standard installation location is the upper part of the refrigerator compartment, often hidden behind a lampshade or plastic cover.
To get to the unit, it is usually necessary to remove the temperature control knob, which is located outside. After removing the handle, you need to carefully unscrew the mounting screws holding the inner plastic panel. Under it you will see a metal or plastic thermostat housing with a long capillary tubecoming out of it. This tube is attached to the evaporator or lies freely in the body cavity, reacting to the general temperature background.
In some models, for example, in a number of modifications Indesit or Stinol, the thermal relay can be shifted to the side, closer to the door opening or niche above the top shelf. Fastening is carried out using special clips or screws that must be unscrewed to remove the device. Be careful when working with the capillary tube: it is filled with freon and is very thin; its damage will lead to a refrigerant leak and the need to call a technician for refilling.
- 🔍 Upper corner: Most often, the unit is hidden in the upper left or right corner of the refrigerator compartment.
- 💡 Behind the lampshade: Light bulb often blocks access to the thermostat mounting screws.
- 🔧 Under the handle: The temperature regulator can be removed along with the shaft, allowing access to the insides.
- ❄️ On the evaporator: The tip of the sensing tube is always attached to the cooling element.
Search for sensors in two-chamber models and No Frost
In two-chamber refrigerators, the situation is complicated by the presence of separate cooling circuits for the refrigerator and freezer compartments. In systems No Frost thermal sensors (thermistors) are located directly in the air channels through which cold air circulates. Their task is to read the temperature of the air, and not the surface of the evaporator, as in drip systems.
In the freezer, the sensor is often located behind the back wall, hidden by a plastic panel. To access it, you need to remove all the drawers and shelves, unscrew the screws that secure the back wall, and carefully unclip the plastic latches. The thermistor itself is a small cylinder or disk mounted in a special hole in the air duct. In the refrigerator compartment, the sensor can be located in the upper part of the rear wall or be built into the control unit if it is located in the upper part of the case. Electronic control modules in modern models often combine temperature control functions. In such cases, there is no “thermal relay” as a separate mechanical unit. Instead, several thermistors are used, connected to a single board. One sensor controls the temperature of the evaporator (to prevent freezing), the other controls the air temperature in the chamber, the third can be responsible for the super-freezing mode.
Electronic control modules in modern models LG, Samsung or Bosch temperature control functions are often combined. In such cases, there is no “thermal relay” as a separate mechanical unit. Instead, several thermistors are used, connected to a single board. One sensor controls the temperature of the evaporator (to prevent freezing), another monitors the temperature of the air in the chamber, and the third can be responsible for the super-freezing mode.
System type Location Sensor type Difficulty of access Drip (Old) Inside the chamber, behind the panel Mechanical thermostat Low Drip (New) Inside the case or behind the back wall Electronic thermistor Medium No Frost Air ducts for freezer and refrigerator Thermistor High Full No Frost Separate channels, often behind panels Several thermistors High Why is the sensor hidden deeply?
Manufacturers place sensors in hard-to-reach places not to complicate repairs, but to protect them from mechanical damage when loading products and ensure the accuracy of readings in the area of active air circulation, and not at the door, where the temperature constantly fluctuates.
Dismantling and visual inspection of the element
Once you have determined where is the thermostat in the refrigerator your model, you can begin to remove it. This process requires care and compliance with safety precautions. The first step is to completely turn off the power to the appliance by unplugging the power cord from the outlet. Any manipulation with live electrical components is deadly.
The process of dismantling the mechanical thermostat begins with removing the adjustment knob. It may be a tight fit, so use a flathead screwdriver to pry it loose, but don't use too much force to avoid breaking the plastic. Next, unscrew the fastening nut or screws holding the housing. When removing the block, carefully monitor the capillary tube: it should not have any kinks or cracks.
If we are talking about an electronic thermistor, then after removing the protective panel you will need to disconnect the connector. Often the connectors are secured with additional latches that need to be pressed out with your fingers or a thin tool. Do not pull on the wires; hold only the plastic part of the connector. After removal, carry out a visual inspection: there should be no traces of burning, contact oxidation or insulation melting on the case.
- 🛑 De-energizing: Always unplug the cord from the outlet before starting work.
- 📸 Fixation: Take a photo at each stage of disassembly so as not to forget anything during assembly.
- 🔌 Contacts: Check the terminals for oxidation and tightness of the wires.
- 🧊 Tube: Make sure that the capillary tube of the mechanical relay is intact and not deformed.
Diagnostics of thermal relay faults
Just finding the part is not enough, you need to understand whether it is working. The most reliable way to check a mechanical thermostat is to use a multimeter in dial mode. At room temperature, the contacts of a conventional thermostat (normally closed) should ring, that is, the device should show a short circuit (resistance close to zero). If the multimeter is silent, it means that the contacts are burnt or broken, and the relay must be replaced.
For a more accurate diagnosis of a mechanical relay, you can conduct a cold immersion test. Carefully, without damaging the tube, place the sensitive end of the thermostat into a container with cold water and ice (temperature about 0...+2°C). After a few minutes, the contacts should open and the multimeter should stop beeping. If this does not happen, it means that the calibration or tightness of the bellows is broken, and the relay will not turn off the compressor, which will lead to freezing of the products.
Electronic thermistors are checked by measuring their resistance at different temperatures. The resistance values depend on the specific sensor model, but usually at room temperature it is several kiloohms (for example, 5-10 kOhm), and when frozen it increases sharply. If the multimeter shows an open circuit (infinity) or a short circuit (zero) regardless of the temperature, the sensor is faulty.
☑️ Checking the thermal relay with a multimeter
Done: 0 / 5⚠️ Attention: Characteristics thermistors (temperature coefficient of resistance) may differ from manufacturer to manufacturer. When replacing, it is important to buy a sensor with a similar marking, otherwise the refrigerator will not work correctly, or the control system will go into error.Replacing and setting up a new regulator
If diagnostics confirm a malfunction, the only solution is to replace the element. When installing a new mechanical thermostat, it is extremely important to position the capillary tube correctly. It should fit tightly to the evaporator in the same place where the old one was attached, and be secured with a standard clip. Insufficient contact will lead to a delayed response to temperature changes and large differences.
In electronic systems, replacing a thermistor is usually simpler: a new sensor is installed in the seat and connected to the connector. However, after replacement, errors in the controller memory may need to be reset. To do this, sometimes you need to leave the refrigerator unplugged from the network for 15-20 minutes, or perform a special combination of buttons on the control panel, which is described in the instructions for a specific model Electrolux or Haier.
After assembling and turning on the equipment, do not expect an instant result. The refrigerator needs time (from 2 to 6 hours) to reach operating mode and stabilize the temperature. During this period, the compressor may work longer than usual or take longer pauses - this is a normal process of adjusting thermal conditions. If the temperature does not stabilize after a day, perhaps the problem was not only in the thermostat.
Independent repair of a refrigerator is a task that requires care and basic skills in working with tools. Understanding where the thermostat is located and how it functions allows you to independently troubleshoot a number of common faults, such as continuous operation of the compressor or lack of cold. However, if you are not confident in your abilities or diagnostics have shown complex electrical problems, it is better to contact professional technicians.
Frequently asked questions (FAQ)
Is it possible to temporarily close the contacts of the thermostat so that the refrigerator starts working?
Technically, you can close the contacts and the compressor will start working, but do this categorically not recommended for long-term use. In this case, the refrigerator will operate continuously, without shutdowns, which will lead to icing of food, overload of the compressor and possible failure. This is only permissible as a short-term measure for defrosting or diagnostics.
Why does the refrigerator not turn on after replacing the thermostat?
There may be several reasons: the wires are incorrectly connected (the circuit is mixed up), the new thermostat is faulty (defective), or the problem lies not in the relay, but in the compressor start relay or the engine itself. It is also worth checking the presence of voltage in the socket and the integrity of the fuses.
How to understand that it is the thermal relay that has broken down, and not the compressor?
If the compressor hums, but does not start, or starts for a couple of seconds and clicks, the problem is most often in the start relay or the compressor. If the compressor is silent, but when you turn the thermostat knob to minimum, you hear a click and the equipment starts, most likely the thermostat is faulty. Also, a sign of a faulty thermal relay is the continuous operation of the refrigerator without shutdowns.
Where can I buy a suitable thermal relay for my model?
It is best to look for spare parts using the full model code of your refrigerator (indicated on the nameplate inside the chamber or on the back). Spare parts can be found in specialized household appliance stores, service centers or on online platforms specializing in components for repair.