Improper operation of refrigeration equipment is often associated with a simple error in the settings, and not with a compressor breakdown or freon leak. Many owners of household appliances are faced with a situation where the food in the chamber either freezes, turning into ice, or, conversely, begins to quickly deteriorate due to insufficient cold. The basis for maintaining an optimal microclimate is thermostat a device that automatically starts and stops the compressor depending on the specified parameters.
Understanding the operating principle of this unit allows you to save energy and extend the service life of the unit. If the temperature is set too low, the motor will run continuously, which will lead to overheating and wear. On the other hand, setting it too high will cause the food to melt. Adjustment can be made using both external handles and internal screws, access to which requires partial disassembly of the case.
In this article we will look in detail at where the adjustment mechanism is located in various models, how to understand that the settings have gone wrong, and what steps need to be taken to correct them.
The principle of operation and types of thermostats
The main task of the thermostat is to control the temperature inside the refrigerator or freezer. Structurally, most mechanical devices are a sealed tube filled with gas or liquid that responds to changes in temperature. When heated, the gas expands, the pressure in the tube increases, and the membrane opens the electrical contacts, starting the compressor. When cooling, the reverse process occurs.
There are two main types of devices: mechanical and electronic. In mechanical thermostats the setting is made by turning the handle, which physically changes the spring tension, affecting the response threshold. Electronic models are controlled through a control panel on the door, where the signal is supplied from temperature sensors. Electronics are considered more accurate, but mechanics are highly reliable and maintainable.
It is important to distinguish between household and industrial settings. For home use, the temperature range usually varies from +2 to +8 degrees Celsius in the refrigerator compartment. Freezer compartment requires significantly lower values, often down to -18 degrees and below. Incorrect calibration can cause the refrigerator to operate in an inefficient cycle.
Location of adjustment elements in different models
Finding the adjustment point depends on the manufacturer and year of manufacture of the equipment. In old Soviet-made models, such as Atlant or Biryusa, the thermostat is often hidden behind a plastic cover inside the chamber or displayed on the outer panel in the form of a rotary knob with numbers. In modern units Liebherr or Bosch the control is most often placed on the display, but mechanical adjustment is possible through special holes.
In two-chamber systems with one compressor, the thermostat usually controls the temperature in the refrigerator compartment, and the freezer is cooled due to the redistribution of cold. In such cases, the adjustment affects both cameras at once. If a system is used No Frost, the sensors can be located in the evaporator area, and not directly in the food compartment.
To access the internal adjustment, you often need to remove decorative elements. For example, in some models Indesit it is necessary to dismantle the lampshade or remove the top cover of the housing. Always disconnect the device from the mains before starting any work to find the adjusting screws.
When it is necessary to adjust the thermostat
There are a number of signs indicating that the current settings are lost or the device is not working correctly. The first signal is the formation of excessive ice or “fur coat” on the back wall of the chamber. This indicates that the compressor is running too long without shutting down on time. In this case, products may freeze to the shelves.
The second sign is insufficient cooling. If the milk sours faster than usual, and the chamber feels like room temperature, perhaps the thermostat “does not see” the heat and does not start the motor. The third case is replacing the thermostat itself. After installing the new part required fine adjustment, since the factory parameters may not correspond to the characteristics of your specific compressor and the volume of the chambers.
⚠️ Attention: If after replacing the thermostat the refrigerator begins to operate jerkily (turns on for 10 seconds and turns off for 5 minutes), adjustment carried out incorrectly. This can quickly damage the compressor.
Adjustment is also required when changing the climate class or installation location of the unit. If you move your refrigerator from a cool hallway to a hot kitchen, the old settings may no longer be effective. In summer, it is often necessary to increase the cold, and in winter, to weaken it in order to compensate for external temperature changes.
Step-by-step instructions for adjusting a mechanical thermostat
The process of setting up a mechanical device requires precision and the availability of tools. You will need a flathead screwdriver, a thermometer to check the result, and possibly a multimeter for diagnostics. Before starting work, make sure that the refrigerator is empty or the food has been moved, since access to the screws often requires freeing up space.
☑️ Preparing for adjustment
Find the adjusting screw. It can be located on the thermostat body itself (often this is a small hole under the seal) or can be located on the control knob. Turning the screw clockwise usually increases the spring tension, which causes the compressor to turn on at higher temperatures (the mode becomes “cooler”). Counterclockwise - weakens the tension, increasing the shutdown temperature.
Turn the screw very smoothly, literally 10-15 degrees (half a turn or less). A sudden change in setting will result in the system not having time to stabilize. After each intervention, it is necessary to let the refrigerator run a full cycle - turn on, cool the chamber and turn off. This may take from 30 minutes to several hours.
For precise adjustments, use an external thermometer, placing it in a glass of water on the middle shelf. Aim for readings around +4°C. If the thermostat has an adjustment range, make sure that the extreme positions of the handle correspond to the actual turning on and off of the motor.
Features of setting up electronic control systems
In modern models with electronic control, physical adjustment of the thermostat is replaced software calibration. The user sets the desired temperature through the interface, and the controller itself controls the operation of the compressor and fans. However, even such systems may require resetting or calibrating the sensors.
A special combination of buttons is often required to enter the service menu (engineering mode). For example, in some models Samsung you need to simultaneously hold down the lock and mode selection buttons for a few seconds. In the menu you can find parameters for setting the evaporator temperature or hysteresis (difference between on and off temperatures).
Be careful when changing factory parameters in the service menu. Incorrect setting of values can lead to incorrect operation of the system No Frost or defrosting. If you are not sure of the values, it is better to perform a full factory reset (Reset) rather than experiment with numbers.
| Parameter | Standard value | Impact on operation |
|---|---|---|
| Evaporator temperature | -10..-14°C | Defines the defrost frequency |
| Compressor operating time | Depends on the model | Continuous operation limit |
| Hysteresis | 2-4 degrees | Difference between on and off. |
| Temperature in the chamber | +4°C | Target cooling value |
Typical errors and fault diagnosis
A frequent mistake when adjusting is an attempt to “increase” the cold, when the problem lies not in the thermostat, and in a freon leak or condenser contamination. If you turn the knob to maximum and the refrigerator is barely cold, most likely the thermostat has nothing to do with it. In this case, further adjustment will only wear out the motor, but will not solve the problem.
Another mistake is ignoring the condition of the door seals. If the rubber does not fit tightly, warm air constantly enters the chamber. The thermostat will “think” the refrigerator is hot and will cause the compressor to run non-stop. Before adjusting, be sure to check the tightness of the door.
How to check the tightness of the door?
Take a sheet of paper and clamp it with the refrigerator door. If the sheet can be easily pulled out without effort around the entire perimeter, the seal requires replacing or adjusting the hinges.
It is also worth considering that some thermostats have a factory seal on the adjusting screw. Failure to comply may result in loss of warranty. If the unit is under warranty service, any interventions in the internal mechanics should be carried out only by certified specialists.
⚠️ Attention: Do not try to adjust the thermostat if you hear a burning smell or see sparks. This is a sign of an electrical malfunction that requires professional repair.
Checking the result and final calibration
After completing all manipulations, it is necessary to carry out a control measurement. Leave the refrigerator in operating mode for 24 hours. During this time, it will go through several cycles of on and off, and the temperature will stabilize. Use a thermometer placed in the center of the chamber, away from the walls and ventilation holes.
The optimal mode is when the compressor takes up about 30-40% of the operating time (turn-on ratio). That is, if the cycle lasts 1 hour, the motor should run for approximately 20-25 minutes and rest for 35-40 minutes. If the motor hums constantly or turns on too rarely, the screw adjustment procedure will have to be repeated.
Write down the final position of the screw or setting so that in the future you will know which parameters are suitable for your device. Regularly checking the temperature regime will help keep food fresh and avoid unnecessary energy costs.
Is it possible to adjust the thermostat of a working refrigerator?
Technically, you can turn it external handle on the operating device, but access to the internal adjustment screw requires unplugging. Internal adjustment is carried out only on a de-energized device to avoid electric shock.
Why did the refrigerator stop turning off after adjustment?
Most likely, you tightened the adjusting screw too much, increasing the spring tension. Now the pressure in the bellows is not enough to open the contacts. Try making a few turns of the screw in the opposite direction.
How can you tell that the thermostat is broken and the settings are not lost?
If, when you turn the knob all the way in both directions, there is no click and the compressor does not respond (or works constantly), most likely the device is faulty. Also a sign of a breakdown is the lack of response to changes in temperature inside the chamber.
Do I need to call a technician for adjustment?
If we are talking about an external handle - no, you can do it yourself. If you need access to the internal screw under the seal or adjustment of the electronic module, it is better to contact a specialist so as not to violate the warranty and not damage the components.