A sudden failure of the refrigerator is always stressful, especially when there are perishable foods in the chamber. Often the cause of a breakdown is the failure of the starting device, which is responsible for starting the compressor engine. In domestic and many imported models of refrigeration equipment, a thermal relay is widely used RKT 2, known for its reliability, but it is not immune to wear.
Replacing this element requires care and understanding of the operating principle of the electrical circuit. Incorrect connection can lead to burnout of the electric motor windings or complete failure of the compressor. In this article, we will analyze in detail the process of diagnostics, dismantling the old device and installing a new relay, so that you can carry out the repair yourself.
Before taking active steps, you need to make sure you have basic tools and follow safety precautions. Working with high voltage electrical devices requires complete shutdown equipment from the network. Even a short-term closure of contacts under voltage can lead to serious consequences for the health of the master.
Diagnostics of a malfunction of the starting relay
The first sign that the relay RKT 2 has failed is the characteristic clicking sound, followed by the hum of the compressor, but the unit itself does not start. After a few seconds, the thermal protection is triggered, a second click is heard, and the refrigerator goes silent. This cycle can be repeated endlessly until the device is de-energized. This indicates that the starting winding does not receive the necessary impulse to start the engine rotor.
For accurate diagnostics, it is necessary to remove the relay from the compressor housing. It is usually attached to three pins protruding from the bottom of the motor. Visual inspection can reveal melting of the plastic, blackening of the internal contacts, or the presence of carbon deposits. If the relay body has cracks or signs of overheating, its operation is impossible and requires immediate replacement.
Checking the integrity of the coil and contacts is performed using a multimeter. The coil resistance must be in a certain range, usually from 30 to 200 Ohms, depending on the modification. Open circuit or, conversely, a short circuit (resistance close to zero) indicates a malfunction of the element. The mobility of the core is also checked - it should move freely inside the coil and return to its original position under the influence of gravity.
⚠️ Attention: If after replacing the relay the situation has not changed, the problem may lie in the compressor itself. Jamming of the piston group or interturn short circuit of the motor windings requires professional intervention or replacement of the unit.
Sometimes the cause of failure is not the relay itself, but oxidation of the contacts on the connector. Cleaning the contact pads with fine sandpaper can temporarily restore functionality, but this is only a half-measure. Guaranteed result only installing a new certified component that meets the technical specifications of your refrigerator can be done.
Preparation for replacement and necessary tools
High-quality repairs are impossible without properly selected tools. To replace the relay RKT 2 you will need a minimum set that most men have in their homes. However, the use of specialized tools will make the process safer and more convenient.
First of all, make sure that you have a working multimeter to test the circuit. Without this device, it is difficult to guarantee that the new relay is working properly and the connection is made correctly. You will also need pliers with insulated handles and a screwdriver to remove the protective cover of the compressor compartment.
- 🛠️ A set of screwdrivers (phillips and flat) for dismantling the casing.
- 🔌 A multimeter or tester for testing contacts.
- 🧤 Dielectric gloves for protection against residual current.
- 🔦 Flashlight for illuminating the back wall of the refrigerator.
It is important to choose the right relay to replace. Models RKT 2 can have various modifications, differing in response current and type of fastening. There is always a marking on the body of the old relay, for example, RKT 2-1 or RKT 2-2. The number after the hyphen indicates the range of currents for which the device is designed.
When buying a new part, pay attention to the condition of the terminals. They must be clean, without oxides and deformation. Plastic case should not have chips, as this can break the seal and lead to moisture getting inside the mechanism.
Connection diagram and contact markings
Understanding the connection diagram - the key to a successful renovation. The relay RKT 2 has several contacts, each of which is responsible for a specific function in the compressor starting circuit. An erroneous connection of even two wires can lead to a short circuit.
The relay body is usually marked with a diagram or letter marking of the contacts. The main designations that you will encounter: L (Line) - common phase wire, R (Run) - working winding, S (Start) - starting winding. In some modifications, instead of letters, numbers or color coding of wires may be used.
For ease of perception of information about the purpose of contacts, we present a correspondence table:
| Designation | Purpose of contact | Wire color (typical) | Function in the circuit |
|---|---|---|---|
L or 1 |
Line (Phase) | Brown / White | Power supply from the mains |
R or 2 |
Working winding | Black / Red | Maintaining engine operation |
S or 3 |
Starting winding | Blue / Green | Starting the compressor rotor |
C |
Common | Yellow | Grounding the housing (rarely) |
Therefore always navigate on the diagram printed directly on the relay or in the technical documentation for your refrigerator model. Visual correspondence of the location of the pins on the relay and the compressor connector also plays an important role.
If you are using a universal relay instead of the original RKT 2, carefully study the attached instructions. Universal models often have a more complex connection system and may require additional configuration or selection of adapters.
What happens if the contacts of the starting and operating windings are mixed up?
If the contacts are mixed up, the starting winding will be under constant voltage, and not just at the time of start-up. This will lead to its rapid overheating, melting of the insulation and probable combustion of the winding within a few minutes of compressor operation.
Step-by-step instructions for installing the RKT 2 relay
The process of replacing the relay requires sequential operations. Failure to do so may result in damage to new parts or injury. Follow the algorithm to ensure a reliable connection and long service life of the repaired unit.
Start by disconnecting the refrigerator from the power supply. Unplug the unit and move the unit away from the wall to gain access to the rear panel. Remove the compressor protective cover by unscrewing the mounting screws or releasing the latches. You will see a view of the motor-compressor with a relay and capacitor attached to it.
☑️ Algorithm for replacing the relay
Carefully remove the old relay. It is held on by three pins on the compressor and possibly secured with a bracket or clamp. Do not use excessive force to avoid damaging the copper tubes or wires. Make a note or take a photo of which wire was connected where. This will be your basic assembly instruction.
Install the new relay RKT 2 in place of the old one. Make sure it fits snugly on the pins and locks into place. Connect the wires according to the previously made diagram or marking. If you use connectors, make sure that they are fully inserted onto the relay contacts and are not loose.
⚠️ Attention: The RKT 2 relay has a strictly defined installation position (usually the “UP” arrow should face up). Installing the relay upside down will disrupt the operation of the thermal release and can lead to accidents.
After connecting all the wires, visually check the assembly again. Make sure that no wires touch hot parts of the compressor or moving parts. Put on the protective cover and secure it. Now you can plug in the refrigerator and listen to it start.
Checking operation and typical errors
After successful installation of the relay, it is necessary to conduct a test run of the system. Plug in the refrigerator. You should hear a characteristic click from the relay, followed by the smooth hum of the compressor running. If the launch was successful, after some time (10-15 minutes) the walls inside the chamber should begin to cool.
Pay attention to the behavior of the relay in the first minutes of operation. It should not emit extraneous sounds, crackling or humming, different from the noise of the motor. Housing heating a relay is allowed, but it should not be critical - it should be possible to touch without getting burned.
- ❌ The compressor hums, but does not start - it may be connected incorrectly contacts or relay does not correspond to the power of the motor.
- ❌ A crackling sound is heard inside the relay - a sign of poor contact or a defective mechanism.
- ❌ The compressor starts and immediately stalls - thermal protection is triggered, possibly due to overload or malfunction of the motor itself.
One of the typical mistakes is ignoring the state of the capacitor. When replacing a relay RKT 2 it is strongly recommended to check the starting capacitor, which is often paired with the relay. Its swelling or loss of capacity can nullify all efforts to replace the relay.
If after replacing the relay the refrigerator is unstable, do not rush to blame the new part. Check the mains voltage - low voltage may prevent the compressor from starting normally even with a working relay. Also make sure that there are no leaks in the refrigerant circulation system.
Technical characteristics and compatibility
Relay RKT 2 is not a universal solution for all compressors. It is designed for engines of a certain power and type. Using a relay with unsuitable characteristics will either make it impossible to start or lead to rapid failure of the new element.
The main compatibility parameter is the rated current. For RKT 2 it usually varies between 1.3 - 1.8 Amperes, depending on the specific modification (the number in the marking). It is also important to consider the type of compressor: piston and rotary engines may require different types of starting devices.
The table below shows examples of compatibility of RKT series relays with popular compressor models:
| Relay model | Rated current (A) | Compressor type | Compatible brands |
|---|---|---|---|
RKT 2-1 |
1.3 | Piston | Atlant, Indesit, Ariston |
RKT 2-2 |
1.6 | Porshnevoy | Biryusa, Pozis, Nord |
RKT 2-3 |
1.8 | Porshnevoy | Samsung (old), LG |
RKT 2-4 |
2.2 | Piston | Powerful Atlant models |
When looking for analogues, pay attention to the geometric dimensions. The seat on the compressor is standardized, but the height of the relay housing may vary. A relay that is too tall may not fit under the protective casing or may rest against the capacitor tubes.
Modern refrigerators are increasingly equipped with inverter compressors, for which the relay RKT 2 is not suitable. Such systems use electronic starting devices (inverters), the operating principle of which is fundamentally different from electromechanical relays. Therefore, before purchasing, make sure that your refrigerator is equipped with a conventional piston motor.
Frequently asked questions (FAQ)
Can I use the RKT 2 relay from another refrigerator?
The relay can only be used if if its current marking and geometric dimensions completely coincide with the original. Different models of compressors consume different starting current, and a discrepancy can lead to breakdown.
Why did the new relay immediately burn out after installation?
There may be several reasons: incorrect connection of contacts, jamming of the compressor (mechanical blocking), power surges in the network, or defective parts of the new part itself. It is also possible that the starting capacitor is faulty.
How long should the relay operate before turning off?
The starting relay RKT 2 works only when the compressor starts (1-3 seconds). After the engine speeds up, the starting winding is turned off and the relay goes into standby mode. The thermal relay inside the case is triggered only when overloaded.
Can the RKT 2 relay be repaired or just replaced?
Relays of this type are considered disposable elements. The internal structure (bimetallic plate, coil, contacts) is not subject to high-quality restoration at home. It is cheaper and more reliable to buy a new part.
Is it dangerous to change the relay in the refrigerator yourself?
The replacement process is not complicated, but requires compliance with safety precautions. The main danger is 220V electric current. If you are not confident in your abilities or do not have basic skills in working with electrical appliances, it is better to contact a professional technician.