Stopping the refrigerator is always stress, especially when food melts in the chamber and the silence in the room becomes suspicious. Often the cause of a breakdown is the failure of the starting device, which is responsible for starting the internal circuit engine. Start relay is a key element of the electrical circuit, without which the compressor either will not turn on at all or will work with constant interruptions. Understanding how to correctly connect the relay on the refrigerator compressor will allow you to fix the malfunction yourself and save a significant amount on calling a technician.
Modern household refrigerators, be it Indesit, Atlant or Bosch, use similar principles for constructing the electrical circuit of the motor. However, the visual design and type of fastening may vary significantly. In this article, we will analyze in detail the structure of the mechanism, diagnostic methods and a step-by-step replacement algorithm so that you can confidently carry out repairs.
Before starting any work, you must completely de-energize the household appliance. Electrical safety is the first rule, violation of which can lead to serious injury or damage to the electronics. Unplug the plug from the socket and move the unit away from the wall, providing access to the rear panel.
⚠️ Attention: If you notice melted wires or smell a persistent smell of burnt plastic, do not rush to install a new part. First, check the integrity of the compressor windings, since a short circuit could occur inside the motor itself.
Diagnostics of a faulty starter
Before looking for a diagram of how to connect a relay on a refrigerator compressor, you need to make sure that the problem lies in this particular unit. Symptoms can be different: the motor hums, but does not start, or it turns on for a few seconds and immediately turns off with a characteristic click. Start-protective relay often fails due to voltage surges or natural wear of the contact group.
Visual inspection can tell a lot to an experienced person to the master. Remove the housing from the back of the compressor and remove the plastic box containing the wires. If inside you see traces of burning, blackened contacts or smell sour, then the part definitely requires replacement. It is also worth checking the condition of the wires for oxidation.
- 🔍 Symptom 1: The refrigerator hums for 5-10 seconds, then there is a click and silence (thermal protection is triggered).
- 🔌 Symptom 2: The compressor is completely silent, although the indicators are lit in the chamber warm.
- 🌡️ Symptom 3: The relay body becomes very hot or has a melted appearance.
For more accurate diagnostics, you can use a multimeter. Check the contacts for a short circuit or open circuit. In good condition, the resistance should be minimal, and the contacts should close at a certain position of the part. If you are not confident in your abilities, it is better to replace the part with a known good one to check.
Types of starting relays and their design
There are two main types of devices used in household refrigerators: induction (electromagnetic) and posistor. Induction relay works on the principle of electromagnetic induction: when voltage is applied the coil draws in the core, closing the starting winding. After the engine starts, the current drops, and the core opens the circuit under the influence of gravity.
Posistor relay (thermal) is a more modern and common solution. Inside it there is a ceramic element - a posistor, which, when heated, sharply increases its resistance, breaking the starting winding circuit. Such details are often called PTC relay. They are less sensitive to the position of the refrigerator, which is important during transportation.
What is the difference between relays for single-phase and two-phase compressors?
Domestic refrigerators use single-phase compressors with a starting winding Two-phase systems are extremely rare in household appliances and require a completely different connection scheme, usually industrial equipment.
It is important to understand that these devices are not always interchangeable. Installing a posistor relay instead of an induction relay (or vice versa) without taking into account the characteristics can lead to combustion of the compressor windings. It is critically important to select a replacement strictly according to the catalog number or technical characteristics of the original.
Structurally, the relay consists of a housing, a coil (or posistor), contacts and sometimes a capacitor. The capacitor helps smooth out the starting current and make it easier to start the engine under load. If your model has it, it should also be checked for swelling or electrolyte leakage.
Connection diagram and contact marking
The most difficult step for a beginner is to figure out which wire to connect where. There are usually markings on the relay housing and the compressor itself, but they may be erased or unclear. The standard connection diagram includes three main contacts on the compressor, arranged in a triangle.
Usually the contacts are designated by letters or symbols. Contact "C" (Common) is the common wire to which the phase fits. Contact "R" (Run) is the working winding, and contact "S" (Start) - starting winding. In some models Atlant or Biryusa marking may be different, for example, Roman numerals I, II, III are used.
| Designation on the diagram | Contact function | Wire color (standard) | Location on the triangle |
|---|---|---|---|
| C (Common) | Common power input | Red or White | Top or left top |
| R (Run) | Working winding | Green or Blue | Right top |
| S (Start) | Start winding | Black or Yellow | Bottom top |
| GND | Case ground | Yellow-green | Separate screw on the body |
When removing the old relay, it is recommended to photograph the location of the wires or sketch the diagram. An error in connecting the starting and operating windings can lead to the compressor humming but not spinning, which will quickly damage it. If there is no marking, use a multimeter in continuity mode: the resistance between the working and common windings is always less than between the starting and common windings.
Step-by-step instructions for replacing the relay
The replacement process does not require complex tools, but does require accuracy. First you need to remove the protective casing from the compressor. It is usually held in place by latches or a single screw. After removing the casing, you will see the compressor itself and a plastic block attached to it on the side or top - this is our desired device.
Disconnect the terminal block with the power wires. It can be fixed with a latch, which must be carefully pressed out with a flat-head screwdriver. Then remove the relay itself from the compressor contacts. It simply slides onto the three pins, but may be tight due to oxidation or heat. Rock it from side to side, avoiding sudden jerks so as not to damage the copper tubes.
☑️ Algorithm for replacing the relay
Installing the new element is done in the reverse order. Push the relay onto the compressor contacts until it stops. Make sure it sits straight and doesn't wobble. If the model requires a specific position (for example, an arrow UP up), be sure to comply with this requirement, especially for induction types. Then connect the block with wires.
⚠️ Attention: Some manufacturers use unique connectors. If the new part does not fit the shape of the connector, do not try to force the wires in. It is better to carefully re-solder the contacts or use reliable terminal blocks, observing polarity.
After connecting all the wires, check the reliability of the connections again. Wires should not touch hot parts of the compressor or sharp metal edges. Secure them if necessary with plastic clamps. Only after a visual check can you proceed to a test run.
Test run and operation check
Before placing the refrigerator in place, it is necessary to conduct an initial test. Plug the plug into the outlet. You should hear the relay click (if it is electromagnetic) and the motor start. The compressor should start smoothly, without vibrations or humming. Starting current In the first seconds it may be high, but then it stabilizes.
Put your hand on the compressor housing (be careful, it may vibrate). If the motor is running, after 10-15 minutes the lower part of the compressor will begin to heat up. This is normal workflow. If the compressor clicks and turns off again, immediately turn off the power. This is a signal that either the relay is not suitable, or the problem is deeper (for example, a compressor wedge).
- ✅ Normal: Smooth hum, heating of the case, stable operation without stopping.
- ❌ Pathology: Frequent clicks every 10-20 seconds, no heating, burning smell.
- ⏱️ Time: Let the refrigerator run idle for 30-40 minutes before loading food.
If everything went well, install the protective casing in place. Make sure it is securely fastened and does not block the ventilation openings. Now you can move the refrigerator to the wall, maintaining the necessary clearances for ventilation, and load the food.
Frequent errors when connecting
Even experienced craftsmen sometimes make mistakes, let alone beginners. The most common mistake is ignoring the relay position. For induction models, orientation in space is critical: if the relay is turned over, the core will not be able to return to its original position under the influence of gravity, and the starting winding will not turn off.
Another mistake is using an inappropriate replacement. Externally, a relay from LG may be similar to a relay from Indesit, but have different current characteristics. Installing a relay that is too powerful will result in it not opening the circuit and the winding will burn out. Too weak - it will constantly knock out the protection.
The capacitor is also often forgotten. If there was one in your circuit, but you did not connect it or connected it incorrectly (reversed the polarity if it is polar), the engine will experience overload at start. Always check for the presence of a capacitor in the circuit.
What will happen if you mix up the working and starting windings?
The compressor will start in the opposite direction or will not start at all. In the best case, thermal protection will work, in the worst case, the starting winding will burn out due to overheating, since it is not designed for long-term operation.
Compatibility table and selection of analogues
When looking for a replacement, it is important to focus not only on the brand of the refrigerator, but also on the model of the compressor. Manufacturers often change component suppliers. Below is a table of correspondence between relay types for popular brands of compressors.
| Compressor brand | Relay type (original) | Analogue (universal) | Power (W) |
|---|---|---|---|
| Secop (Danfoss) | 101N0011 (posistor) | 101N0011 / R6 | 1/6 - 1/5 hp |
| Atlant | RTK-N (Inductive) | RTK-N / 3314922 | 1/5 - 1/4 hp |
| Embraco | PTC Start Relay | Universal 220V | 1/4 hp |
| LG / Samsung | Kit with capacitor | By catalog number | 1/5 hp |
When purchasing a universal relay, pay attention to the power range. The range is often written on the case, for example 1/6 - 1/4 HP. Your compressor should fall within this range. The power of the compressor is usually indicated on a nameplate glued to the metal body of the motor.
Is it possible to install a relay with a higher power than the original?
Technically, a more powerful relay can start the compressor, but this is risky. It may not open the circuit in time, which will lead to overheating of the starting winding. It is better to look for an exact analogue or a universal relay with an adjustable range where your motor falls.
Why does a new relay burn out immediately after installation?
This may indicate a malfunction of the compressor itself (turn-to-turn short circuit), problems with the wiring of the refrigerator, or power surges in the network. Also, the reason may be the incorrect orientation of the relay in space.
Is it necessary to change the capacitor along with the relay?
It is advisable, especially if the old capacitor looks swollen or is more than 10 years old. The capacitor loses capacity over time, which increases the load on the starting system and shortens the service life of the new relay.
How to understand that the problem is not in the relay, but in the compressor?
If, when replacing the relay and checking the voltage at the input, the compressor still does not start, hums and quickly heats up, or if the resistance of the windings shows zero or infinity - a breakdown or wedge of the motor is likely.
Where can I find the markings on the relay?
The markings are usually applied to the side or top edge of the plastic case with black paint. Look for codes like 101N..., RTK... or indicating the power in horsepower (HP).