A sudden stop of the compressor or, conversely, its continuous operation without shutting down often indicates a failure of the temperature control system. In most cases, the culprit of such anomalies is the thermal relay (thermostat), which ceases to respond correctly to changes in the temperature regime inside the chamber. If you notice that food begins to deteriorate due to lack of cold or, on the contrary, freezes, turning into ice, you cannot ignore the problem - this is a direct threat to the performance of the entire unit.
Replacing this component is one of the most accessible procedures for a home craftsman, which does not require complex specialized equipment. However, despite its apparent simplicity, the process requires attention to the details of electrical connections and strict adherence to safety precautions. Incorrect installation or selection of an incompatible model can lead to a short circuit or failure of an expensive compressor.
In this article we will analyze in detail the algorithm of actions that will allow you to independently diagnose the malfunction and replace the unit. You will learn how to choose the right analogue, what tools you will need for the job, and what design nuances of your refrigerator refrigerator you should pay special attention to before disassembling.
Diagnostics of thermostat malfunction
Before disassembling the equipment, you need to make sure that the problem It lies precisely in the thermostat, and not in a freon leak or a malfunction of the start relay. The first sign of a breakdown is often the absence of a characteristic click when changing the position of the temperature regulator. If you turn the adjustment knob, but the compressor does not start and does not make any sounds, this is an alarming signal.
There are several indirect signs that indicate the need for intervention in the thermoregulation system. These include:
- ❄️ The compressor works without interruption, even when it is clearly too cold inside the chamber.
- 🔌 The engine does not start at all, although there is voltage in the network and the light is on.
- 🌡️ The temperature in the chamber differs significantly from the set temperature regulator.
- 💧 The appearance of ice or a “snow coat” on the rear wall when the engine is running.
For more accurate diagnostics, you can use a multimeter in dial mode. At room temperature, the contacts of some thermostats may be closed, but when cooled (for example, if you place the sensor in the freezer), they may open. If the circuit does not respond to temperature changes, defect obvious. It is also worth checking the integrity of the bellows tube: if it is damaged and the filler gas has come out of it, the device will not work.
⚠️ Attention: Before any manipulations with electrical components, be sure to unplug the refrigerator! Residual voltage or an accidental short circuit can lead to serious injury.
Sometimes the cause of incorrect operation is not the mechanism itself, but a displaced capillary tube. It should fit tightly to the evaporator in a specially designated place. If the contact is broken, the thermal relay “does not sense” the real temperature in the chamber.
Selection of a suitable replacement model
The success of the repair directly depends on the correctness of the selected spare part. The thermal relay is not a universal component, and installing an unsuitable analogue can lead to incorrect temperature conditions. The main reference point is the markings on the body of the old device. Even if the relay is visually similar, the parameters may differ.
When looking for a replacement, pay attention to the following critical parameters:
- 🔢 Model number or the article number specified by the manufacturer (for example, K59, TAM133, DANFOSS).
- 📏 Length capillary tube (measured in centimeters, accuracy up to 1-2 cm is important).
- 🔌 Type of contacts and terminal arrangement (2 or 3 terminals, grounding).
- 🌡️ Operating temperature range (for a refrigerator or freezer).
If you find the exact original is not It seems possible, it is permissible to use universal analogues, but only if the electrical characteristics match. Often, craftsmen use thermostats of the K59 or TAMseries, which are suitable for many models of Atlant, Indesit and Beko refrigerators. However, in such cases, it may be necessary to adjust the length of the tube or change the trigger point.
Can a thermal relay be used with a longer tube?
Yes, you can. If the capillary tube of the new relay is longer than that of the old one, it can be carefully twisted into a ring (at least 5 cm in diameter) and placed inside the housing. The main thing is not to bend the tube and not damage its integrity. It is strictly forbidden to shorten the tube!
It is also important to consider the type of fastening and the shape of the case. Some models have special tabs or holes for screws that must match the seat in your unit. A mismatch in geometry can complicate installation and disrupt the heat exchange between the tube and the evaporator.
Necessary tools and preparation of the workplace
For a quality replacement of the thermal relay, the arsenal of a professional service engineer is not required, but a basic set of tools must be prepared. The work ahead is delicate and requires accuracy, so it is better to clear the space around the refrigerator in advance and provide good lighting.
You will need:
- 🔧 A set of screwdrivers (phillips and flathead of different sizes).
- 🔪 Pliers or pliers for working with clamps.
- 📷 Smartphone or camera for recording the wiring diagram.
- 🧤 Dielectric gloves for additional safety.
Pay special attention to the organization of lighting. The internal cavities of the refrigerator, especially in the evaporator area, are often shaded by plastic panels. Using a headlamp or a powerful lamp will greatly simplify the process of dismantling old fasteners and installing a new thermostat.
Prepare a container for defrosting in advance if during work you need to bend the elements of the cooling system, and they will have time to become overgrown with ice. Although complete defrosting is not always necessary, having rags and a basin on hand never hurts.
☑️ Ready for repair
Step-by-step instructions for dismantling the old relay
The replacement process begins with access to the installation site of the thermostat. In most modern models, it is located inside the refrigerator compartment, often hidden behind a decorative panel or lampshade. In older models, the relay may be located outside, at the rear of the unit.
Algorithm for internal location:
- Remove the temperature regulator by pulling the handle toward you (sometimes you must first remove the plastic stopper or screw).
- Remove the plastic cover covering the thermostat housing. It can be secured with latches or screws.
- Carefully remove the relay body, being careful not to damage the capillary tube.
- Take a photo of the location of the wires on the terminals so as not to confuse them when connecting.
- Disconnect the wires and remove the terminal grounding (yellow-green wire), if present.
The most delicate step is removing the capillary tube from the channel in the evaporator. It is usually secured with a metal bracket or pressed down with a bar. It is necessary to loosen the fastening and very carefully, without jerking, pull out the tube. Excessive force can lead to its breakage, which will require complex repairs with recharging the system.
⚠️ Attention: The capillary tube is filled with gas under pressure. If it is damaged, gas will escape and the new relay will become unusable. Avoid kinks and creases in the tube when removing.
If the thermal relay is located outside (in a plastic box on the back wall), the task is simplified: just remove the casing, unscrew the fastening screws and disconnect the wires. However, in this case, the tube passes through the wall of the refrigerator, and its tightness cannot be broken when removing it - simply disconnect the relay from the tube, if the design allows, or carefully push it inside.
Installation of a new thermostat and connection
Installation of a new device is carried out in the reverse order of dismantling. The key point is the correct placement of the capillary tube. It should be placed exactly the same as the old one: in the same channel, under the same clamping bars. The accuracy of temperature reading depends on this.
When connecting the electrical part, be guided by the photographs taken earlier. If there is no photo, use the color marking of the wires, which often (but not always!) corresponds to the standard:
| Wire color | Function | Where to connect |
|---|---|---|
| Red / Orange | Phase (power) | Relay input terminal |
| Black / Brown | Compressor | Motor start terminal |
| Yellow / Green | Grounding | Housing or special. terminal |
| White / Blue | Lamp / Fan | Lighting circuit terminal |
Make sure the contacts are firmly seated on the terminals. Oxidized or loose connections can cause sparking and heating, which is dangerous for the plastic parts of the refrigerator. After connecting the electrics, carefully thread the tube into the channel and secure the relay housing in place.
The final step is the installation of decorative panels and handles regulator Don’t rush to turn on the refrigerator right away—let all the elements fall into place. Check that nothing interferes with the closing of the door and the operation of the internal mechanisms.
Checking functionality and setting
After assembly, you need to test the system. Plug in the refrigerator and set the regulator to the middle position. After 10-15 minutes you should hear a click and the compressor will start. If this does not happen, check the connection diagram again - perhaps the input and output are mixed up.
Evaluate the operation of the unit for several hours. The temperature in the main chamber should stabilize in the range of +2...+5°C. If the refrigerator “does not freeze” or, on the contrary, freezes food in the refrigerator compartment, additional adjustment may be required. Some thermostat models have an adjusting screw under the seal, which allows you to shift the temperature range.
Pay attention to the operating cycle: the compressor must be turned off periodically. Continuous operation indicates that the relay does not “see” the dialed temperature (problem with the tube) or a device with the wrong range has been selected.
If after replacement the problem does not disappear, perhaps the malfunction is complex (freon leakage, compressor failure) and requires the intervention of a professional with a vacuum pump and pressure gauges.
Common mistakes during self-repair
Even following the instructions, beginners often make typical mistakes that nullify all efforts. One of the most common is damage to the capillary tube due to careless handling. This is a fatal mistake that turns a simple repair into a complex and expensive one.
Other common mistakes:
- ❌ Ignoring grounding, which can lead to an electric shock when touching the case.
- ❌ Loose fit of the tube in the channel, due to which the thermostat reacts with great force delay.
- ❌ Using electrical tape instead of securely connecting the terminals, which leads to oxidation.
- ❌ An attempt to shorten the capillary tube, which violates the physical properties of the filler.
⚠️ Attention: Do not try to repair the thermostat housing or seal the capillary tube at home. This is a sealed system, and a violation of its integrity makes the device unusable.
Also, you should not install the relay “at random”, without checking the contacts. Poor contact is a fire risk. Always check that all connections are firmly secured before final assembly.
Questions and answers (FAQ)
Is it possible to install a thermal relay with a shorter capillary tube?
No, this is impossible. A capillary tube is a sealed system filled with gas. Shortening it will lead to depressurization and gas escape, after which the thermostat will stop working. If the tube is too long, you can carefully roll it into a ring, but you cannot reduce the length.
Why does the refrigerator turn on and off immediately after replacing the relay?
This may indicate several problems: the type of relay is incorrectly selected (wrong temperature range), a malfunction of the new relay (defect), or the problem is not in the thermostat, but in the compressor start relay or motor windings. It is also possible that there is a short circuit in the wiring.
Where can I find the thermostat marking if it is erased?
If the marking on the body is not readable, try to find the model of your refrigerator (on the sticker inside the chamber or on the back) and use the service manual or on the Internet to find out what type of thermostat was installed there. You can also rely on photos of similar models on the Internet, paying attention to the length of the tube and the location of the contacts.
Is it necessary to defrost the refrigerator before replacing?
Full defrosting is not always necessary if access to the relay is opened without compromising the integrity of the evaporator. However, if ice interferes with access to the fastenings of the capillary tube, it is better to let the refrigerator stand unplugged for several hours so that the ice melts and does not damage the plastic parts during dismantling.
What is the difference between a thermostat for a single-chamber and a two-chamber refrigerator?
The main difference is in the response temperature range. For the refrigerator compartment the range is usually from +4 to +10°C, and for the freezer - from -15 to -24°C. Installing the wrong relay will result in food either melting or freezing.