A sudden stop of the compressor or a characteristic click followed by the engine not starting often indicates a malfunction of the starter protection device. It is this small but critical component that is responsible for starting the engine and protecting it from network overloads. If you notice that the refrigerator is humming but not cooling, or the compressor is heating up and immediately turns off, there is a high probability that it is time to replace this element.
Replacing a part yourself is a real opportunity to save on calling a technician, since the process requires only a minimal set of tools and a basic understanding of the structure of electrical appliances. However, before starting any manipulations, it is necessary to clearly understand the risks associated with electric current and strictly observe safety precautions when working with live household appliances.
In this article we will analyze in detail the algorithm of actions that will allow you to carefully dismantle the old device, diagnose it and install a new working element. The correct approach to repair will extend the life of your refrigerator and restore its functionality in the shortest possible time without extra costs.
Principle of operation and types of starting relays
The starting relay is an electromechanical switch that supplies voltage to the starting winding of the compressor only at the moment of startup. As soon as the motor rotor reaches the required speed, the device opens the starting winding circuit, allowing the motor to operate on the main winding. In modern refrigerators, two main types of such devices are most often found: induction (electromagnetic) and posistor.
Induction relays they work due to an electromagnetic coil, which, when current is supplied, draws in the core, closing the contacts of the starting winding. When the current decreases (when the engine starts), the core falls under the influence of gravity, opening the circuit. Such models are often marked indicating the installation orientation, since they are sensitive to position relative to the horizon.
Posistor relays are more modern and do not have moving mechanical parts inside. Their work is based on the property of a posistor (thermistor) to sharply increase its resistance when heated. At the moment of switching on, a cold posistor passes current, starting the engine, then heats up and almost completely breaks the starting winding circuit. This technology is considered more reliable and less susceptible to wear from mechanical shocks.
⚠️ Attention: An attempt to install a relay that is not intended for a specific compressor model may lead to burnout of the motor windings. Always check compatibility using the catalog number or technical specifications.
Understanding the type of your device is important not only for replacement, but also for initial diagnosis. Induction relays often emit an audible click when trying to start, while posistor relays can be quieter, requiring careful listening to the operation of the unit.
Necessary tools and safety measures
Before you begin (disassembling) the back of the refrigerator, you need to prepare a workplace and tools. You don’t need complex industrial equipment; just a set of home tools that any home craftsman can find. The main thing is to provide yourself with convenient access to the bottom of the unit, where the compressor is located.
The basic set of tools includes:
- 🔧 Screwdrivers (Phillips and flat) for removing protective covers and terminals.
- 🔪 Knife or flat spatula for neatly removing stuck-on parts elements (if required).
- 🔦 Flashlight for good illumination of the working area in the compressor niche.
- 🧤 Dielectric gloves for protection from residual current and sharp edges.
- 📱 Smartphone with a camera for photographing the connection diagram before dismantling.
The most important stage of preparation is de-energizing the device. Unplug the power cord from the outlet and make sure no one accidentally turns it on while you are working. It is also recommended to let the refrigerator stand turned off for a while so that the capacitors are discharged and the refrigerant in the system is stabilized.
Inspect the back wall of the refrigerator for visible damage to the wire insulation. If you find melted areas or exposed wires, further work should be carried out with extreme caution or entrusted to a professional. Never touch the copper tubes of the compressor with your hands if the refrigerator has just been running - the temperature there can reach 80-90 degrees Celsius.
Access to the compressor and removal casing
In order to remove the relay, you must gain physical access to the compressor, which is usually located in the lower rear of the refrigerator. In most modern models, access is closed with a special protective cover or casing, which is secured with latches or screws. The process of removing this protection is the first step to a successful repair.
Carefully move the refrigerator away from the wall to give yourself room to maneuver. Below you will see a metal or plastic panel covering the engine compartment. If the panel is attached with screws, use a suitable screwdriver. If it is held on by latches, they need to be carefully squeezed out, trying not to break the plastic, which could become fragile over the years of use.
After removing the panel, you will see a view of the compressor - a round black “cylinder” with tubes and electrical wires going to it. The relay is usually placed directly on the side or lower rod of the compressor and is covered with an additional small plastic box.
☑️ Preparation for removing the relay
In some models, for example, Indesit or Ariston, access can be further limited by structural elements of the frame. In such cases, it may be necessary to partially unscrew the fastenings of the compressor itself, but this must be done extremely carefully so as not to break the tightness of the cooling system.
Removing the old start relay
The process of removing the relay from the contacts of the compressor itself requires accuracy and a steady hand. The device sits tightly on three contact pins extending from the motor housing, and is often additionally secured with a metal bracket or plastic clip. Incorrect force can lead to breakage of the plastic housing of the relay or, worse, damage to the contacts of the compressor.
First you need to disconnect the wires going to the relay. There are usually two or three of them, and they are connected via terminal blocks. Before pulling the wires, carefully inspect the design: some terminals have locking tabs that need to be bent. Remember or take a photowhich wire is connected where, since the color markings do not always meet the standards.
If the relay is held in place by a metal bracket, it must be released or removed. Then grab the relay housing with both hands (or with one hand while holding the compressor) and try to pull it down with a loosening motion from side to side. Do not pull sharply upward or sideways, so as not to break the ceramic insulators inside the compressor.
In cases where the relay has become “stuck” due to time and high temperature, you can use a small amount of penetrating lubricant (for example, WD-40), applying it to the junction of plastic and metal, but trying not to splash it on the electrical contacts. After the contaminants have softened, the removal attempt can be repeated.
⚠️ Attention: When removing the relay, make sure that you do not damage the compressor tubes. Copper is very soft, and careless movement with a screwdriver can lead to freon leakage, which will make repairs economically impractical.
After successful dismantling, inspect the inside of the relay. If you see traces of burning, melted plastic, or smell burnt insulation, the diagnosis is confirmed - the device requires replacement. Also check the condition of the contacts on the compressor itself: they should be clean and not oxidized.
Diagnostics and performance testing
Before throwing away the old relay or installing a new one, it makes sense to carry out simple diagnostics to verify the cause of the malfunction. Often the problem lies precisely in mechanical sticking of the contacts or destruction of the posistor. To check, you may need a multimeter set to continuity or resistance measurement mode.
Checking the induction relay:
- 🔍 Visually inspect the contacts for carbon deposits or welding.
- 🔌 Check the mobility of the core: it should move freely inside coils.
- 📉 Ring the circuit: in the vertical position the contacts should close, in the horizontal position they should open.
Checking the posistor relay:
- 🌡️ In the cold state, the posistor resistance should be low (about 10-50 Ohm).
- 🔥 When heated (you can gently warm it with a hairdryer), the resistance should increase to infinity.
- 🔊 Shake the relay: if something dangles inside, it means the posistor has collapsed.
Is it possible to temporarily start a refrigerator without a relay?
Theoretically, you can start the compressor by applying voltage directly to the starting winding, but doing this is strictly not recommended without special skills. This can lead to burning of the windings or a fire, since the relay performs a protection function.
If the multimeter shows an open circuit where there should be a short circuit, or vice versa - a short circuit, the device is faulty. Also a sign of a malfunction is the absence of a characteristic click when power is applied (for induction models). The table below shows the main symptoms and their probable causes.
| Symptom | Probable cause | Action |
|---|---|---|
| Clicking, silence, buzzing | Contacts stuck or the posistor burned out | Replacing the relay |
| The compressor is hot, does not start | Faulty relay or jammed motor | Checking the relay and starting torque |
| Frequent on/off | Thermal protection has tripped | Checking the load and relay |
| Smelling a burning smell from the engine compartment | Overheating of contacts | Urgent replacement of the device |
Installation of a new relay and testing
Installation of a new device is carried out in the reverse order of removal. The most important thing here is to correctly orient the relay relative to the compressor. There is always an arrow or inscription on the body of the new relay, which should look straight up. This is especially critical for induction models where gravity is involved in opening the contacts. UP, TOP, which should look straight up. This is especially critical for induction models where gravity is involved in opening the contacts.
Carefully slide the relay onto the contact pins of the compressor. It should fit tightly and with slight effort. Make sure all three pins fit into their sockets. If the relay has a metal retaining clip, return it to its place and snap it into place. Then connect the wires to the terminals, based on the photographs you took earlier or the diagram on the case.
After assembling all electrical connections, but before installing the protective casing, you can conduct an initial test. Plug in the refrigerator. You should hear the compressor start confidently. If the motor hums smoothly and after a while the tubes begin to heat up (input and output), it means that the launch was successful.
Do not rush to close the casing immediately. Observe the operation of the unit for 10-15 minutes. Make sure that the relay does not spark, make unusual noises, or become excessively hot. If everything goes well, install the protective panel in place and screw it.
Frequent replacement errors and expert advice
Despite the apparent simplicity of the operation, beginners often make mistakes that can negate all efforts. One of the most common is ignoring the markings and installing the relay “as it happens.” This leads to the fact that the device either does not work or does not work correctly, without disconnecting the starting winding, which leads to overheating and combustion of the compressor.
Another common mistake is ignoring the condition of the wires. If the wires going to the relay have damaged insulation or oxidized contacts, the new relay will not last long. Be sure to check the integrity of the wiring and, if necessary, clean the contacts or change the terminals. Poor contact causes sparking and heating, which is the main reason for the failure of starting devices.
Also, you should not try to “reanimate” the old relay by stripping the contacts or tapping. Even if after such manipulations the refrigerator starts, the effect will be temporary. The internal structure of the posistor or the parameters of the coil have already been damaged, and a repeated failure will occur at the most inopportune moment, possibly leading to more expensive repairs.
⚠️ Attention: The characteristics of compressors and relays may vary even within the same refrigerator model, depending on the year of manufacture. Always check the parameters of the new device with the markings on the old one.
If after replacing the relay the problem does not disappear (the compressor hums, but does not start, or the machine in the panel knocks out), the compressor itself (an interturn short circuit or wedge) or the capacitor may be faulty. In this case, independent repairs can be completed, and the intervention of a specialist with equipment for diagnosing motors will be required.
What to do if the new relay does not fit the mounts?
Sometimes manufacturers change component suppliers. If the connectors match, but the housing does not fit into its normal place, you can carefully modify the plastic housing of the relay or use insulating tape for fixation, the main thing is to ensure reliable contact at the compressor terminals.
FAQ: Frequently asked questions
Is it possible to start the refrigerator directly without a relay?
Theoretically, you can start an asynchronous motor by applying a phase to the starting winding through a capacitor or a button, but it is dangerous to do this at home. Without a protection relay, the compressor can burn out in a few seconds if it becomes jammed or overloaded. This is a temporary measure for diagnostics, but not for permanent operation.
How to understand that it is the relay that has burned out, and not the compressor?
If you hear a click when you turn it on, then a buzzing sound, and after a few seconds a second click is heard (the thermal protection relay is activated), and the compressor is hot - most likely the problem is in the starting relay or starting winding. If the compressor is silent or hums, but does not try to start, and does not heat up, the windings may be broken or the relay may be faulty. An accurate diagnosis will only be obtained by testing the windings with a multimeter.
Where can I buy a suitable relay for my refrigerator?
You need to look for the markings on the body of the old device (for example, PTC, RKT, 117N, etc.). You can buy it in spare parts stores for household appliances, at radio markets, or order online using the catalog number. Universal relays are also sold, but require selection according to the power of the compressor.
Why does the relay heat up during operation?
Posistor relays in operating mode can be warm (up to 60-70 degrees), since a current passes through them, maintaining a high resistance. However, if the relay gets so hot that the plastic melts, this indicates a malfunction (the starting winding circuit does not open) or an incorrect selection of the device.
How much does it cost to replace the relay in a service center?
The cost consists of the price of the part itself (usually from 300 to 1500 rubles depending on the model) and the cost of work masters Self-replacement allows you to save on a specialist visit and work, since the operation itself takes 15-20 minutes.