A sudden stop of the compressor and silence that reigns in the kitchen instead of the usual humming often indicates a failure of the starting device. It is this small but critical element that is responsible for starting the electric motor, supplying the necessary impulse to the starting winding. If your refrigerator has stopped freezing, and the motor either does not start at all, or hums for several seconds and clicks while trying to start, the problem in 90% of cases lies in start-protective relay.
Before running to the store for a new part, it is necessary to carry out initial diagnostics to make sure that the problem is in the relay, and not in the relay itself. compressor. In older models with open motors, relays with a posistor were often used, which over time lost their properties or were destroyed by vibration. Modern units can be equipped with more complex electronic modules, but the principle of their replacement remains similar. It is important to understand that relay replacement is a procedure available to the home handyman, but requires compliance with safety precautions and accuracy of actions.
In this article we will look in detail at how to determine the type of faulty element, how it can be replaced with a similar one, and what parameters are critical when selecting. You will learn why universal parts are not always suitable and how to correctly read the markings on the body of a burnt device. A competent approach will extend the life of your refrigerator and avoid an expensive call to a repairman.
Fault diagnosis and signs of breakdown
The first and surest sign of a malfunction is the characteristic sound that the refrigerator makes. You can hear the compressor trying to start: there is a dull hum that lasts 3-5 seconds, followed by a loud click. After this there is silence, and the cycle repeats after a certain time. This sound indicates that starting winding receives power, but the engine cannot turn over, and the thermal protection is triggered.
Visual inspection can also tell a lot about the condition of the part. If you get to the relay and see traces of carbon deposits, melted plastic on its body, or smell a burning smell, then replacement is inevitable. Often you can find scattered powder inside the case - this is a burnt posistor or charred contacts. In some cases, the relay may “stick” when turned on, causing the compressor to work without interruption, causing overheating and freezing of the evaporator.
⚠️ Attention: Before any manipulations with the electrical components of the refrigerator, be sure to disconnect the device from the network. Residual voltage may remain in the capacitors, and careless handling of wires under load will lead to electric shock.
Diagnostics can be carried out by exclusion. If you have a multimeter, check the integrity of the compressor windings through the relay connectors. The resistance between the starting and operating windings should be within normal limits (usually from 20 to 40 ohms in total). If the resistance is infinitely high or, conversely, close to zero (short circuit), the problem may be deeper, and simply replacing the relay will not help. Also check the posistor itself: when cold, its resistance should be low (several Ohms), and when heated, it should go to infinity.
Classification and types of starting relays
Understanding what kind of device is installed in your refrigerator is the key to successful repairs. There are two main types of mechanical relays that most often fail: induction (electromagnetic) and posistor. Induction relays were usually installed on old-style refrigerators running on R12 freon and have a vertical location. Their operation is based on the closure of contacts under the influence of current in the starting winding.
Posistor relays, or relays with a posistor, are more modern and widespread. They work due to the property of a semiconductor element (posistor) to sharply increase its resistance when heated by current. When the refrigerator is turned on, it consumes a large current, the posistor heats up and opens the starting winding circuit. Such devices often have a horizontal layout and three contacts. There are also combined relaysthat combine the functions of a starting element and a thermal release that protects the motor from overheating.
It is especially worth mentioning the electronic starting devices that are found in inverter compressors. They have no moving mechanical parts and are controlled by a microprocessor. Replacing such modules is more difficult and requires selecting an exact analogue based on the catalog number, since there are practically no universal solutions here. For ordinary household refrigerators with a linear compressor, standard mechanical or posistor solutions are most often used.
How to choose an analogue: marking and compatibility
The most reliable way to find a replacement is the marking on the body of the burnt relay. Manufacturers apply special codes that indicate the size, permissible power of the compressor and type of refrigerant. For example, marking RTK or R-3 is typical for Soviet and post-Soviet models, while foreign brands use their own coding systems, such as PTC (Positive Temperature Coefficient). It is important to look for a part with similar or similar electrical characteristics.
When selecting an analogue, pay attention to the following parameters:
- 🔌 Number of contacts: there should be the same number of them as on the original, and they should be located in a similar order.
- 📏 Fitting dimensions: the relay must sit tightly on the compressor terminals, without loosening and without requiring excessive effort for installation.
- ⚡ Engine power: the relay is designed for a certain power range (for example, from 1/8 to 1/4 hp), and exceeding this limit will lead to rapid failure of the new part.
- ❄️ Refrigerant type: Some relays are optimized for working with certain freons (R134a, R600a), which affects the operating temperature.
If found If the exact original is not possible, you can use universal starting relays. They are often sold complete with adapters and a set of terminals, which allows them to be adapted to different compressor models. However, it should be remembered that universal solutions are a compromise. They may operate less stably or have a shorter lifespan compared to original components designed specifically for a specific series of engines.
Where can I find the markings on the relay?
The markings are usually applied to the side or top edge of the plastic housing. If the inscription is erased or covered with dirt, try gently wiping the surface with alcohol. Sometimes the code is indicated on the metal cover, which must be removed (after turning off the device!).
The table below shows common types of relays and their possible analogues, which will help you navigate your search:
| Original type | Characteristics | Possible analogue / Universal | Application |
|---|---|---|---|
| RTK-X (1, 2, 3) | Induction, vertical | RTK-1, RTK-2 (with selection) | Refrigerators Biryusa, Minsk (old) |
| R-3 (R-4) | Posistor, 3 contacts | PTC 11-15, PTC 22-30 | Atlant, Indesit, Ariston |
| (Danfoss type) | Posistor, 3 contacts | Universal PTC with terminals | Foreign models, Liebherr |
| 103N0011 | Combined | Selection by motor power | Modern models Electrolux, Zanussi |
⚠️ Attention: Using a relay with the wrong power (too powerful or too weak) may cause the contacts to stick or, conversely, not close. This is fraught with combustion of the compressor windings.
Step-by-step instructions for replacing the relay
The replacement process begins with providing access to the compressor. To do this, you need to unplug the refrigerator, pull it out into free space and remove the back metal panel. At the bottom you will see a black round tank - this is the compressor itself, and the required relay is attached to its side or top. Carefully remove the fixing bracket or unscrew the screws holding the protective box.
Next follow the procedure:
1. Take pictures of the wire connections before disconnecting them. This will help avoid errors during assembly.
2. Disconnect the wires from the relay terminals. If they are stuck, use pliers, but be careful not to damage the insulation.
3. Remove the old relay from the compressor terminals. It may fit tightly, so slightly rock it from side to side.
☑️ Checklist before installing a new relay
Installation of the new element is carried out in the reverse order. Push the relay onto the three pins of the compressor as far as it will go. Make sure it sits level and not askew. Connect the wires according to the photograph or diagram you took earlier. If you are using a universal relay with adapters, make sure that the phasing (L, N, Start, Run) is correct. After assembly, turn on the refrigerator and listen: the start-up should be soft, without strong clicks or buzzing.
The nuances of installing universal relays
Universal starting relays (often labeled as Universal PTC Start Relay) are a salvation when the original is out of production. However, their installation has its own characteristics. The main difference is in the mounting system: instead of a rigid fit on the compressor terminals, they often require the use of additional terminals or extension wires included in the kit.
When installing a universal relay, it is important to correctly determine the purpose of the contacts. They are usually designated by letters: M (Main/Run) - working winding, S (Start) - starting winding, C (Common) - common contact. An error in the connection can lead to a short circuit or the motor running on only one winding, which will cause it to overheat. Carefully study the diagram printed on the body of the new relay or in the instructions for it.
Another important point is orientation in space. Some universal relays are position sensitive (only work vertically or horizontally). If after installation the refrigerator hums but does not start, try turning the relay 90 or 180 degrees. Also check whether the new device is overheating during operation - slight heating is normal, but a hot body indicates a problem.
Frequent errors and precautions
One of the most common mistakes is ignoring the reason for the failure of the old relay. If the compressor has an interturn short circuit or a jammed piston, it will consume increased current, which will lead to the combustion of even a new, working relay in a matter of minutes. Therefore, if after replacement the situation repeats, do not rush to change the relay again - check the motor itself.
Also, technicians often forget about thermal protection. In combination relays it is built-in, but if you are changing only the starting part, make sure that the thermal relay (bimetallic plate) is in good condition and fits tightly to the compressor housing for correct temperature reading. Loose contact will result in the protection not working in time and the engine will burn out.
⚠️ Attention: Refrigeration equipment specifications and parts availability may vary. Manufacturers can change the design of compressors within the same model. Always check the visual conformity of the part and the electrical parameters before final installation.
Do not forget about the cleanliness of the contacts. Oxidized or burnt terminals create additional resistance, causing heat and sparking. Clean the contacts with fine sandpaper or a file before installing the new relay. This is a simple procedure that will significantly increase the reliability of the connection.
Questions and answers (FAQ)
Is it possible to solder a burnt relay or restore it?
Theoretically, you can try to disassemble it relay, clean the contacts or replace the posistor. However, the factory seal will be broken, which will lead to moisture and dust getting inside. Under conditions of vibration and temperature changes, such recovery will be temporary. It is more reliable and safer to install a new element, the cost of which is usually low.
Why does a new relay burn out a few days after replacement?
This is an alarming signal. The main reasons: jamming of the compressor (the motor cannot turn over and draws a huge current), an interturn short circuit in the motor windings or incorrect selection of relay power (too weak for the given motor). Also, the cause may be a power surge in the network or a faulty wiring of the refrigerator.
What is the difference between the relay for R12 and R134a?
The difference lies in the operating temperature and materials. Freon R134a requires the use of synthetic oils, which are more hygroscopic, and the system operates at different pressures. Relays for R134a often have improved insulation and are designed to work with compressors of lower power, but with higher requirements for system tightness.
How much does it cost to replace a relay with your own hands?
The cost of the relay itself varies from 300 to 1500 rubles, depending on the model and manufacturer (original or analogue). Tools (screwdriver, pliers, multimeter) are usually already at home. Thus, savings on the services of a specialist can range from 2,000 to 5,000 rubles.