Modern refrigerators Indesit, despite the diversity of the model range, are often based on time-tested mechanical control systems. The central element of this system is the thermostat, which is often called the “heart” of the refrigerator. It is this small device that is responsible for maintaining a given temperature regime inside the chambers, closing and opening the electrical circuit of the compressor depending on the sensor readings.
An understanding of how this unit functions is necessary for every owner of household appliances. This knowledge allows you to independently diagnose common malfunctions, such as lack of cooling or, conversely, excessive freezing of products, without immediately resorting to an expensive call to a technician. Thermoregulator is not just a switch, but a complex mechanism that responds to the slightest changes in the thermal state of freon or air.
In this In this article we will analyze in detail the internal structure of the device, the principles of its interaction with other refrigerator systems and algorithms for finding breakdowns. You'll learn why clicking noises during operation are normal, but absence of clicks may indicate a serious problem. We will also look at the features of setting up different series of thermostats installed on equipment Indesit.
The principle of operation and internal structure of the thermostat
The basis of the design of a mechanical thermostat is a sealed bellows tube filled with a temperature-sensitive gas or liquid. This element, called a capillary, is located directly in the cooling zone - inside the evaporator or on the rear wall of the chamber. When the ambient temperature changes, the working substance inside the tube expands or contracts, creating pressure on the membrane.
The membrane, in turn, acts on a lever system that physically opens or closes electrical contacts. When the temperature in the chamber reaches the lower threshold, the gas is compressed, the pressure drops, and the contacts open - the compressor turns off. As soon as the products begin to heat up and the temperature rises, the gas expands, the pressure on the membrane increases, and the engine turns on turning on the engine.
It is important to note that thermostats often use an additional mechanism for compensating the ambient temperature. It is necessary to ensure that temperature fluctuations in the kitchen do not affect the accuracy of the readings inside the refrigerator. Some models also provide an electrical contact to force the defrost heater to turn on, which is typical for No Frost or drip defrost systems. Indesit An additional ambient temperature compensation mechanism is often used. It is necessary to ensure that temperature fluctuations in the kitchen do not affect the accuracy of the readings inside the refrigerator. Some models also provide an electrical contact to force the defrost heater to turn on, which is typical for No Frost or drip defrosting systems.
The complexity of the mechanism requires accurate calibration. Inside the housing there is an adjustment screw that changes the spring tension, determining the response temperature range. Inept intervention in this unit can lead to the fact that the refrigerator will stop turning off altogether or will work in too short cycles, which is critical for the life of the compressor.
Types of thermostats used in Indesit refrigerators
Engineers Indesit in different generations of refrigerators they used various modifications of thermostats. The most common are Italian-made devices Ranco and Orbital, as well as Chinese analogues. They differ in the length of the capillary tube, the temperature range of operation and the presence of additional functions, such as a contact for a signal lamp.
One of the key characteristics is the presence or absence of a “zero” on the adjustment handle. Models with a “zero” (for example, series TAM-112) allow you to completely turn off the cooling by opening the circuit in the extreme counterclockwise position. Models without a “zero” (for example, TAM-125) open the circuit only when the minimum temperature is reached, and turning the knob towards the minimum simply reduces the cold.
- 🌡️ Single-chamber models: they are often equipped with thermostats with a short capillary and a shutdown range from -6 to -14 degrees, since the freezer compartment is shared here.
- ❄️ Double-chamber refrigerators: use devices with a wider range, where shutdown occurs at temperatures from -10 to -24 degrees, depending on the energy efficiency class.
- 🔌 No Frost systems: require thermostats with an additional contact to control the heating element defrosting, which distinguishes them from their analogues for static freezing.
When selecting spare parts for repair, it is critical to pay attention to the markings. Even visually identical devices may have different capillary lengths or trigger points. Installing an unsuitable thermostat will result in the refrigerator either not gaining the required cold, or turning food into an ice block.
How to read the thermostat markings?
There are numbers stamped on the body of the device, for example, K59-L1102. The letter "L" indicates the length of the capillary tube (in this case 1.1 meters), and the numbers after it indicate the temperature response mode.
Symptoms of a malfunctioning thermostat
Diagnostics begins with an analysis of the behavior of the refrigerator. If you notice that the food in the main chamber has begun to deteriorate faster than usual or, conversely, the vegetables have become covered with frost, it is worth checking the serviceability of the thermostat. However, these symptoms may also indicate other problems, so an integrated approach is required.
The most obvious sign of failure is the absence of characteristic clicks when turning the temperature control knob. In good condition, when moving the knob from the “maximum” to “minimum” position, a clear click should be heard. If the device is silent, the contacts may be stuck or the bellows tube has collapsed.
⚠️ Attention: If the refrigerator runs continuously for days and does not turn off, and a layer of ice (“fur coat”) has formed inside, this may indicate not only a breakdown of the thermostat, but also a freon leak. In the latter case, replacing the regulator will not help.
Another alarming symptom is the compressor turning on and off too often. This phenomenon is called "clocking". It occurs if the thermostat has lost sensitivity and responds to minimal temperature fluctuations. This mode of operation is extremely harmful for the starting relay and motor windings.
Diagnostics and performance testing
To accurately check the thermostat, it must be removed from the refrigerator. Before starting work, be sure to disconnect the unit from the power supply. Remove the regulator handle, remove the plastic casing and disconnect the terminals. Be careful with the capillary tube - it is very thin and is easily damaged if handled carelessly.
The most reliable way to check is to use a multimeter in dial mode. Connect the probes to the thermostat contacts. At room temperature, the contacts should be closed (the device beeps). Then immerse the sensitive tube in a container of water at room temperature (about 20-25 degrees), and leave the thermostat body itself dry.
If after immersion in warm water (imitation heating) there is no click and the circuit does not open, then the device is faulty. You can also check the reaction to cold: place the tube in the freezer for 10-15 minutes. After removal, while the tube is still cold, the contacts should be open. When heated to room temperature, a click should be heard and the circuit should close.
☑️ Checklist for checking the thermostat
Visual inspection is also important. Pay attention to the condition of the wire insulation and the presence of traces of oxidation on the contacts. Sometimes the reason for unstable operation lies in burnt contacts, which create high contact resistance, causing heating and false alarms.
Table of temperature conditions and settings
Correct setting of the thermostat directly affects the shelf life of products and energy consumption. In refrigerators Indesit the adjustment scale usually varies from 1 (minimum cold) to 5 or 7 (maximum cold). Understanding how the knob position corresponds to the actual temperature helps to avoid mistakes.
Below is a table showing the approximate correspondence between the position of the regulator and the temperature inside the main chamber for standard models. It is worth remembering that actual values may vary depending on the load of the refrigerator and the room temperature.
| Handle position | Temperature in the chamber (°C) | Compressor operating mode | Recommendation |
|---|---|---|---|
| 1 (Min) | +6...+8 | Rare inclusions | For short-term storage of drinks |
| 2-3 (Average) | +3...+5 | Normal cycle | Optimal for daily use usage |
| 4-5 (Max) | +1...+2 | Frequent switching on | For large quantities of food or heat |
| Max / Super | 0...+1 | Continuous operation | Only for quick freezing (temporary) |
The use of the “Super” or maximum cooling mode should be limited in time. If you leave the refrigerator in this mode for several days, the evaporator may become covered with a solid crust of ice, and the compressor will overheat due to the lack of pauses in operation.
Replacement thermostat: step-by-step instructions
If diagnostics confirm a malfunction, replacement is necessary. Buy a similar thermostat model, paying attention to the length of the capillary tube. If the new tube is longer than the old one, the excess can be carefully twisted into a ring, but under no circumstances should you bend or cut it, as this will break the tightness of the system.
The installation process begins with dismantling the old element. Disconnect the terminals, remembering their location (it’s better to take a photo). Carefully remove the capillary tube from its seat in the evaporator. Install the new thermostat, securing it in its original place, and thread the tube into the same hole, ensuring tight contact with the cooling surface.
After connecting the electrical part, assemble the casing and install the handle. Turn on the refrigerator and let it run for 1-2 hours. Check if it reaches temperature and turns off on time. The initial start-up may be accompanied by longer operation of the compressor, since the system needs to return to operating mode.
⚠️ Attention: When installing, make sure that the capillary tube does not touch the moving parts of the fan (in No Frost models) and does not have sharp creases. Damage to the tube will lead to the release of refrigerant and complete inoperability of the refrigerator.
Frequently asked questions (FAQ)
Why does the Indesit refrigerator not turn off after replacing the thermostat?
This may be caused by several reasons: the type of thermostat is incorrectly selected (wrong temperature range), the capillary tube is not seated deep enough, or the problem lies not in the regulator, but in a freon leak or a compressor malfunction.
Is it possible to repair an old thermostat rather than changing it?
It is theoretically possible to clean the contacts or make adjustments screw, but in practice this is a temporary measure. A sealed bellows system cannot be repaired, and the reliability of such repair is extremely low. A complete replacement of the unit is recommended.
How can you tell if the thermostat is “lying” and showing the wrong temperature?
Place a regular liquid thermometer in the chamber. If, with the knob positioned at “3”, the thermometer shows +10°C or -5°C, and the food behaves accordingly (spoils or freezes), then the calibration is broken and the device requires replacement.
Does the temperature in the room affect the operation of the thermostat?
Yes, mechanical thermostats are sensitive to external temperature. If the kitchen is very cold (below +16°C), the refrigerator may not turn on at all, since the sensor “thinks” that it is cold enough inside. For such conditions, special thermostats with compensation are required.