Many users of household appliances don’t even think about what exactly makes the compressor turn on and off at the right time, ensuring the safety of products. At the heart of this process is a small but critical element, which is often simply called a regulator. Thermoregulator or thermostat is a device that continuously reads the temperature inside the refrigerator or freezer and sends a signal to the motor to start or stop.
Understanding what the regulator in the refrigerator regulates is necessary for proper operation equipment. If this mechanism does not work correctly, the products may deteriorate from the heat or, conversely, freeze in the main chamber. Owners of older models It is especially important to know how this unit works, since they most often require manual calibration or replacement.
In this article we will examine in detail the principle of operation of this component, symptoms of its malfunction and methods of self-diagnosis. You will find out why the compressor may hum without interruption or not start at all. The thermostat is the main “brain” that determines the cyclical operation of the refrigeration unit, and without its participation the normal functioning of the system is impossible.
The principle of operation of the thermostat in the refrigeration system
The main task of the device is to maintain the specified temperature range. Inside the device body there is a sensitive element - a bellows tube filled with gas or liquid (freon), which reacts to changes in thermal conditions. When the temperature in the chamber rises above the set threshold, the working substance expands, the pressure in the tube rises, and the contacts close, starting the compressor.
The cooling process continues until the temperature drops to the lower limit. At this moment, the pressure in the bellows drops, the spring opens the electrical circuit, and the engine stops. Operation cycle is a normal operating mode that provides a stable climate for food storage.
In modern models, mechanical thermostats are often replaced by electronic sensors, but the principle remains the same: control and management. However, mechanical devices are considered more reliable and less susceptible to power surges. Electronics allows more precise adjustment of parameters, but is more difficult to diagnose.
Basic functions and settings
The temperature controller in the refrigerator is responsible not only for turning it on and off motor, but also for several additional functions that ensure safety and efficiency. Understanding these functions helps the user to correctly configure the device to suit their needs.
Here are the key parameters that are controlled by this unit:
- 🌡️ On threshold: the temperature at which the compressor starts working.
- 🛑 Shutdown threshold: the value at which the motor stops.
- ⏱️ Cycle duration: total operating time and equipment downtime.
- ❄️ Defrost mode: in some models, the thermostat is involved in starting the evaporator defrost cycle.
The user can change these parameters using the rotary knob or numeric keypad. On mechanical models, the scale is often numbered from 1 to 7, with a higher number representing a lower temperature (colder). It is important not to confuse these numbers with degrees Celsius.
Types of thermostats: mechanics versus electronics
There are two main types of regulators on the household appliances market. Mechanical devices, such as popular models TAM-133 or K-59, work due to the physical expansion of gas. They are distinguished by their simplicity of design, low cost and maintainability. Replacing such an element usually takes no more than 30 minutes.
Electronic thermostats are complex microcircuits with resistance sensors. They transmit data to the refrigerator's central processor. Such systems maintain temperature more accurately, but if they break down, they require professional diagnostics and often replacement of the entire control unit.
The differences between types of regulators can be summarized in the following table:
| Characteristics | Mechanical thermostat | Electronic sensor |
|---|---|---|
| Principle of operation | Physical expansion of gas | Change in resistance |
| Accuracy | Average (error 2-3°C) | High (up to 0.5°C) |
| Repair cost | Low | High |
| Maintainability | High | Low (changed more often unit) |
The choice of regulator type depends on the class of the refrigerator. Reliable mechanics are still widely used in budget and mid-range models. Premium brands are switching to complete electronic digitalization of control processes.
Symptoms of a malfunctioning temperature controller
You can determine that the controller has failed by a number of characteristic signs. The most obvious is the lack of cold when the compressor is running or, conversely, the endless operation of the motor without shutdowns. In the first case, the contacts could oxidize and stop closing, in the second, they could stick in a closed state.
It is also worth paying attention to the condition of the products. If bottled water or vegetables begin to freeze in the refrigerator compartment, and the regulator is set to minimum, this is a sure sign of a malfunction. The mechanism is “stuck” in the maximum cold position and does not give a command to stop.
Hidden defect
Why does the refrigerator turn on immediately after turning off?: This may indicate a loss of tightness of the thermostat bellows tube. The gas has evaporated and the pressure inside has dropped, which is why the contacts do not open or close chaotically.
Other alarm signals:
- 🔌 Sparking: when the regulator operates, clicks are heard, accompanied by sparks (visible through the holes in the housing).
- 🌡️ Instability: the temperature in the chamber constantly “jumps” for no apparent reason.
- 🔇 Silence: the refrigerator is silent, although there is voltage in the network, and the light is on (open circuit).
If you observe similar symptoms, it is necessary to carry out a diagnosis. Sometimes the problem is solved by cleaning the contacts, but most often the unit needs to be replaced.
Instructions for self-diagnosis
Before buying a new part, make sure that the problem is in the thermostat. To do this, you will need a multimeter and basic electrical skills. Attention: carry out all work only after completely disconnecting the device from the power supply!
Procedure for checking:
- Get to the thermostat. It is usually located inside the refrigerator behind a plastic panel or at the top, next to the light bulb.
- Disconnect the wires from the terminals of the device. There may be two or three of them (the third usually goes to the light bulb or ground).
- Short the two main wires together directly (using a jumper or twist).
- Plug in the refrigerator.
If, after closing the wires, the compressor starts working and it starts getting cold, it means the motor itself is The starting relay is working properly, but the problem lies in the regulator. If the motor is silent even with the wires closed, you need to look for the fault deeper - in the starting relay or motor windings.
☑️ Checking the thermostat
⚠️ Attention: If you are not confident in your skills in working with electrical appliances, do not carry out diagnostics yourself. Improper handling of wires can lead to a short circuit or electric shock.
Replacing the thermostat with your own hands
Replacing a part is a procedure available to a home craftsman. The main rule is to buy a similar model. Thermostats differ in the length of the capillary tube, the type of fastening and the location of the contacts. An incorrectly selected part may not fit in size or may not work correctly.
The replacement process is as follows:
First remove the old device by carefully pulling the sensitive tube out of the evaporator. It can be attached with latches or simply inserted into the hole. Be careful not to damage the tube of the new device - it is filled with gas under pressure.
Install the new regulator, fixing the tube in the same position as the old one. Immersion depth and bending angle are important for correct temperature reading. Connect the wires according to the diagram (take pictures of the disconnection in advance!).
After assembly, turn on the refrigerator and check its operation for several hours. The compressor must be turned on and off periodically. If the operating cycle is broken, you may need to adjust the screws on the thermostat housing, but this is a task for professionals.
Frequently asked questions (FAQ)
Why does the refrigerator work without stopping after replacing the regulator?
This may mean that the capillary tube is not immersed deep enough in the evaporator or is not in good contact with him. It is also possible that the installed thermostat has different calibration parameters and needs to be adjusted.
Is it possible to temporarily short-circuit the thermostat wires to make the refrigerator work?
Yes, this is possible for short-term preservation of food, but leaving the refrigerator in this mode for a long time is dangerous. The compressor will work continuously, which will lead to its overheating, freezing of the evaporator and spoilage of food due to hypothermia.
How do I know what thermostat number is needed for my model?
The part number (for example, TAM-133) is usually stamped on the metal case of the old device. Information can also be found in the technical documentation of the refrigerator or upon request to the manufacturer's service center, indicating the model of the unit.
Does the room temperature affect the operation of the regulator?
Yes, mechanical thermostats are sensitive to the environment. If the room is very cold (below +10°C), the refrigerator may not turn on at all, since the temperature difference is not sufficient for the mechanism to operate. In hot weather, on the contrary, operation cycles will become more frequent.
⚠️ Attention: Technical characteristics of refrigerators and availability of spare parts may change. Before purchasing a new regulator, always check the labeling with the original or consult official sources of the manufacturer.