When the refrigerator no longer maintains the required temperature, and food begins to deteriorate, the first thing that comes to mind is a compressor breakdown. However, the statistics of service centers indicate the opposite: most often the culprit of an unstable climate is thermostat, in particular, the widespread model RKT 2. This small but critical device is responsible for turning the engine on and off, maintaining the set temperature in the chambers.
Understanding what it is RKT 2 and how it functions will allow you to diagnose the malfunction yourself without causing wizard for a basic check. In this article we will analyze in detail the design of the sensor, its differences from analogues and step by step describe the replacement process, which you can do yourself with a minimum set of tools.
Owners of refrigerators Atlant, Stinol i Indesit it will be especially useful to study the material, since this is where This type of regulator is most often installed in equipment. You will learn why the device clicks, how to correctly set the temperature and what mistakes should not be made during installation so as not to damage the new compressor immediately after installation.
Principle of operation and design of the RKT thermostat 2
Thermoregulator RKT 2 is an electromechanical device that responds to changes in temperature inside the refrigeration chamber. The main working element here is a bellows tube filled with freon or other refrigerant that is sensitive to thermal fluctuations. When the temperature in the chamber rises above a predetermined threshold, the gas in the tube expands, creating pressure on the membrane, which closes the electrical contacts.
This process triggers compressor, beginning the cooling cycle. As soon as the temperature drops to the lower limit, the gas pressure drops, the membrane returns to its original position, and the circuit opens. It is this mechanism that ensures the refrigerator operates cyclically, preventing both overheating of food and the formation of excessive ice. The design RKT 2 is considered one of the most reliable, but over time, mechanical wear or gas leakage from the bellows can lead to failures.
⚠️ Attention: If you hear frequent clicks of the thermostat without starting the compressor, this may indicate sticking contacts or gas leakage from the sensing tube. Further operation in this mode is dangerous for the engine.
It is important to understand that differential temperature (the difference between turning on and off) in the model RKT 2 is fixed or limitedly adjustable. This means you won't be able to change the temperature spread arbitrarily, but you can shift the overall range to lower or higher values using the control knob. The device is sealed, and an attempt to disassemble it for “repair” usually ends in complete loss of functionality, so the unit must only be replaced.
Compatibility and technical characteristics
Thermostat RKT 2 designed to work in single-chamber and double-chamber refrigerators with a drip defrosting system. It belongs to the group of normally open or normally closed contacts (depending on the modification), which requires a careful approach when selecting an analogue. Most often, this regulator is found in manufactured refrigerators Biryusa, Orsk, as well as in older models Atlant.
When choosing a spare part It is necessary to pay attention to the length of the capillary tube. Standard sizes can vary from 0.75 to 1.3 meters. If the tube is too short, it may not be long enough to fit correctly in the evaporator, and if it is too long, it will have to be carefully rolled up, avoiding kinks that could interfere with gas circulation. Voltage specifications are usually 220-240 Volts at a frequency of 50 Hz.
Below is a table that helps determine the main parameters and compatibility of various modifications of RKT series thermostats:
| Thermostat model | Contact type | Capillary length | Compatible brands |
|---|---|---|---|
| RKT 2 | Normally open | 0.75 m | Biryusa, Orsk |
| RKT 2.2 | Normally closed | 0.9 m | Atlant, Stinol |
| RKT 2.4 | Normal open | 1.3 m | Indesit, Ariston |
| RKT 2.9 | Universal | 1.0 m | Samsung (old models) |
Do not forget that the parameters may vary slightly depending on the year of manufacture of the refrigerator. Always check the markings on the body of the old device before purchasing a new one. If an exact model cannot be found, you can use universal analogues, but additional adjustment of the temperature range will be required.
Symptoms of a thermostat malfunction
Fault diagnosis RKT 2 does not always require complex instruments. Often a breakdown manifests itself through a change in the behavior of the refrigerator, which cannot be ignored. The first and most obvious sign is the absence of cold when the compressor is running or, conversely, continuous operation of the engine without shutting down.
Let's consider the main symptoms indicating the need to replace the thermostat:
- ❄️ The refrigerator does not turn on: The compressor is silent, the light is on, but there is no cold. When you turn the thermostat knob, there is no click.
- 🧊 Continuous operation: The engine hums without interruption, a “fur coat” forms in the chamber, food freezes even with the handle at the minimum position.
- ⚡ Short cycle: The refrigerator turns on for 1-2 minutes, then turns off for a long time, without having time to reach the temperature.
- 🔌 None click: When you turn the regulator from minimum to maximum, there is no characteristic click of opening/closing contacts.
It is also worth paying attention to the condition of the products. If the meat in the freezer is soft, and there is a damp smell in the refrigerator compartment, this is a sure sign that thermostat does not give the command to start the compressor when the temperature rises. In some cases, the contacts inside RKT 2 can burn, which leads to sparking and a characteristic burning smell in the area of the back wall.
Instructions for replacing the RKT 2 thermostat
Replacing a thermostat is a procedure that requires care and compliance with safety precautions. Before starting work it is necessary de-energize refrigerator by removing the plug from the socket. You will need a screwdriver (Phillips and flat head), pliers, and possibly a wire stripper. The process begins with dismantling the old part.
First remove the temperature control knob. Usually it is simply pulled together by hand, but in some models it can be secured with a locking screw that needs to be unscrewed. Next, remove the interior panel of the refrigerator compartment to gain access to the thermostat mounting location. The capillary tube RKT 2 is fixed to the evaporator using special clamps - they need to be carefully released.
☑️ Preparing to replace the thermostat
Next follow the algorithm:
- Disconnect the electrical wires from the thermostat contacts, having previously photographed or sketched the connection diagram.
- Remove the sensitive tube from the hole in the chamber, being careful not to damage it or bend it.
- Install a new one RKT 2, securing the housing in its original place.
- Carefully lay the capillary tube along the channel, avoiding sharp creases, and fix it on the evaporator.
- Connect the wires according to the diagram, reliably insulating the twist points.
⚠️ Attention: The capillary tube of the thermostat is filled with gas under pressure. Do not under any circumstances bite it or puncture it, as this will lead to immediate loss of functionality of the new appliance.
After assembling all the panels and installing the handle, you can turn on the refrigerator. The first few cycles of operation may occur with slight deviations in time, as the system needs to reach operating mode. If the compressor starts and turns off after a while, the replacement was successful.
Setting and adjusting the temperature
After installing a new one RKT 2 it may need to be adjusted. The thermostat housing often has adjustment screws hidden under a seal or plug. One screw is responsible for the temperature range (shifts the entire graph), and the second is responsible for the length of the differential (the difference between on/off). For domestic use, it is usually sufficient to adjust only the main switch on the handle.
To set the optimal mode, turn the handle to the middle position and leave the refrigerator to work for 6-8 hours. Then check the temperature of the food. If they freeze slightly, turn the knob towards lower values. If the temperature is too high, move towards higher ones. The stabilization process may take up to 24 hours.
It is important not to confuse setting the thermostat with adjusting the air damper (if your model has one). Thermoregulator controls the compressor, and the damper distributes the cold flows. Incorrect setting RKT 2 can lead to the compressor working for wear, trying to cool the chamber through a closed damper, or, conversely, not turning on when necessary.
Frequent errors during installation and operation
Even experienced craftsmen sometimes make mistakes that shorten the service life of a new thermostat. One of the most common is incorrect placement of the capillary tube. It should fit tightly to the evaporator in a specially designated channel. If the tube hangs in the air of the chamber, the reaction to temperature changes will be delayed, which will lead to large temperature differences and excessive energy consumption.
Another mistake is ignoring the state of the wire insulation. In conditions of high humidity and low temperatures, the insulation becomes brittle. If during replacement you damage the wire braid, be sure to restore it using heat shrink or high-quality electrical tape designed for low temperatures. Ordinary PVC insulating tape can crack and peel off in the cold.
Is it possible to use a thermostat from another model?
The use of analogues is possible if the electrical parameters and type of contacts match (normally open/closed). However, the length of the capillary tube and the temperature range may differ, which will require additional adjustments or lead to incorrect operation of the refrigerator. It is better to look for the original or a complete analogue by catalog number.
Also, users often forget that RKT 2 is sensitive to mechanical shocks. When installing, avoid sudden movements and impacts on the device body. Any deformation of the housing can disrupt the calibration of the internal springs and membranes, making the readings inaccurate.
Why the refrigerator does not turn off after replacement thermostat?
This may indicate several problems: the type of contacts is incorrectly selected (it needs a normally closed one, but it should be open), a gas leak in the new device, or the problem is not in the thermostat, but in a freon leak from the system or a compressor malfunction. It is also possible that the capillary tube is in poor contact with the evaporator.
Where is the RKT 2 thermostat located?
In most models, it is located inside the refrigerator compartment, often hidden by a plastic panel or located under the temperature control knob. In some older models, it can be accessed through the rear wall from the outside, but this is less common.
Is it possible to temporarily short-circuit the thermostat?
Technically, you can connect the wires directly and the compressor will work. However, in this case, the refrigerator will run continuously until you turn it off manually. This will lead to deep freezing of food and possible freezing of the evaporator, as well as overheating of the compressor. Use this method only for a short-term check of the engine's performance.
What is the service life of the RKT 2 thermostat?
The average service life of a high-quality thermostat is 7-10 years or about 20-30 thousand on/off cycles. However, with frequent power surges or mechanical damage (shocks when loading products), this period can be reduced to 3-5 years.