A sudden power outage in the entire house or apartment just at the moment the refrigerator is started is a frightening and extremely unpleasant situation. Most often, the culprit for this reaction of the electrical network is starting relay, which controls the start of the compressor. When this small but critical element fails, it can create a short circuit or a critical overload, causing the circuit breaker (circuit breaker) in the panel to instantly open the circuit.
The situation is aggravated by the fact that many equipment owners initially do not associate knocked-out plugs with a malfunction of the refrigeration unit. They may be due to poor wiring or power surges in the network. However, if you notice a clear pattern - the light goes out at the moment when the refrigerator should turn on to maintain the temperature - the problem lies inside the motor-compressor or in its starting system. Ignoring this symptom can lead to complete combustion of the motor windings, which will make repairs economically unfeasible.
In this article we will analyze the device in detail starting relay, we will analyze the main reasons for its failure and consider how to carry out initial diagnostics. Understanding the physical processes occurring inside the compressor at the time of start will help you make the right decision: call a technician or try to fix the malfunction yourself, having the necessary knowledge and tools.
The principle of operation of the starting relay and its role in the system
To understand why an emergency power outage occurs, you need to understand the functionality start-up relay. This component is responsible for supplying voltage to the starting winding of the compressor motor only at the moment of start. As soon as the rotor reaches the required speed, the relay should turn off the starting winding, leaving only the main winding to work. If this mechanism jams or burns out, the current in the circuit can increase to values exceeding the permissible standards for your home wiring.
There are two main types of such devices found in household appliances: electromagnetic and thermal (posistor). Electromagnetic relays work by changing the current in the winding, which draws in the core and opens the contacts. PTC posistors, more modern ones, use the property of the crystal to change resistance when heated. In both cases, the malfunction leads to the fact that the starting winding remains energized for too long, which causes a sharp jump in energy consumption.
How do relays differ for different compressors?
Relays for inverter compressors have more complex electronic filling and rarely cause simple knockout of the machines, since they are controlled by a board. Classic relays work with asynchronous motors and more often cause short circuits when they fail.
It is important to note that modern refrigerators are equipped with double protection. The first relay is located inside the compressor housing or on its terminal box, the second is a circuit breaker in your electrical panel. When the machine in the apartment breaks, this means that the internal protection of the refrigerator either did not work, or the current increased so quickly and strongly that the apartment machine responded faster. This often happens during interturn short circuit or insulation breakdown.
The main reasons for the machine to knock out during startup
The list of potential culprits for a power outage is quite specific, and knowing them will help narrow down the search. Most often, the problem lies not in the relay itself as a separate part, but in a combination of factors affecting the operation of the motor. The first and most common reason is turn-to-turn short circuit in the windings of the electric motor. In this case, the winding resistance drops, the current increases sharply, and the circuit breaker detects a short circuit.
The second important reason is the failure of the starting relay itself, namely sticking of the contacts. If the contacts are welded or stuck in the closed position, the starting winding receives power continuously rather than briefly. This leads to overheating and an instant increase in current load. It is also impossible to rule out breakdown of the insulation of the wires going to the compressor, or moisture entering the electrical contacts at the bottom of the unit.
The third group of reasons is related to external factors and the condition of the wiring. Oxidation of the contacts at the junction of the relay and the compressor creates additional resistance and heating, which can provoke unstable operation and current surges. In addition, if your house has old wiring with aluminum wires, even a serviceable but powerful refrigerator can create inrush currents, which old machines perceive as an emergency.
Fault diagnosis: symptoms and first steps
Before you begin disassembling the equipment, it is necessary to conduct a visual analysis of the operation of the equipment. Symptoms of a faulty start relay or compressor are usually clear and do not require special equipment for initial detection. Pay attention to the characteristic sounds: if you hear a loud click, followed by a hum, and then another click and the lights go out, this is a classic sign of an attempt to start and then tripping the protection.
Check the temperature of the compressor housing. If the engine tries to start but fails, it may not have time to warm up. However, if the relay is stuck and the engine hums for a long time before the plugs are knocked out, the housing may become hot. Also an important indicator is the smell: the smell of burnt plastic or scorched wiring in the area of the compressor compartment clearly indicates overheating of the insulation or melting of the relay parts.
For more accurate diagnostics, you can use a multimeter, but only if the device is completely disconnected from the network. It is necessary to remove the back cover of the refrigerator, gain access to the compressor and carefully remove the start relay. Checking the integrity of the windings and resistance will help determine whether the engine itself is alive or the problem is solely in the attached equipment.
Instructions for checking and replacing the starting relay
If you decide to carry out diagnostics yourself, you will need a minimum set of tools: a screwdriver, pliers and a multimeter. The process of replacing a relay is not overly complicated, but it requires care and compliance with safety precautions. The main rule is that all manipulations are carried out only with the device completely de-energized.
First you need to remove the protective casing from the compressor. The relay is usually mounted on three pins extending from the motor housing, and is additionally secured with a metal bracket or plastic clips. After carefully disconnecting the wires (after remembering their location), remove the old device. A visual inspection often gives the answer: if soot, melted plastic or a burning smell is visible inside the relay, its replacement is mandatory.
☑️ Algorithm for replacing the relay
When installing a new relay, make sure that it fully matches the model of yours compressor. There are no universal solutions here: the motor power and the starting current characteristics must match. After installation, reassemble the structure in reverse order, but do not install the back cover yet. Plug in the refrigerator and listen: if the motor starts smoothly, without humming and the light does not go out, you can fix the lid.
| Type of fault | Symptom | Probability of repair | Risk for wiring |
|---|---|---|---|
| Sticking relay contacts | Humming, knocking out of the machine | High (relay replacement) | High |
| Breakage of the starting winding | Motor not starts, silence | Medium (rewind) | Low |
| Interturn short circuit | Knocking out plugs, burning smell | Low (motor replacement) | Critical |
| Posistor malfunction | No startup, clicks | High (part replacement) | Medium |
Danger of ignoring the wiring problem
Many users, faced with the machine being knocked out, simply turn it back on and continue to use refrigerator until it turns off the light again. This is an extremely dangerous practice. Each such cycle is a thermal shock to the insulation of wires in the wall. If the wiring is old or faulty, repeated current surges can lead to melting of the outlet, wiki, or even a fire inside the wall.
A circuit breaker is designed specifically to protect against such situations, but it is not a panacea. If the refrigerator relay is faulty, it will create a condition close to a short circuit. Constant operation of the equipment in this mode leads to degradation of the contacts in the switchboard itself, and it may begin to knock out even under normal load in the future.
⚠️ Attention: If after replacing the relay the situation repeats and the switchboard continues to knock out, immediately stop using the refrigerator. There is a high probability that the problem lies in the compressor itself (breakdown on the housing), and further switching on can be a fire hazard.
In addition, it is worth considering the condition of the outlet into which the refrigerator is plugged in. Poor contact in the outlet causes sparking and heating, which can also lead to unstable operation and false protection activations. Make sure that the socket is designed for a current of at least 16 Amps and has no traces of carbon deposits.
When you need to call a professional technician
Despite the apparent simplicity of replacing a relay, there are situations when self-repair is undesirable or dangerous. If you do not have the skills to work with electrical appliances and do not have a multimeter, it is better not to risk it. Incorrect diagnosis can lead to the purchase of unnecessary spare parts or, worse, injury.
A call to a specialist is required if, after replacing the relay and checking the wiring, the refrigerator still knocks out the circuit breakers. This indicates a deeper fault within the compressor, such as a mechanical wedge or a broken winding. In such cases, specialized equipment is required to check the compression and tightness of the system, as well as a possible replacement of the motor-compressor itself.
A technician will also be needed if the refrigerator is located under warranty. Any independent intervention in the design, seals on the compressor or electrical part will lead to loss of warranty. In this case, saving on calling a technician may result in a complete denial of free service.
Prevention and care of the electrical part
To minimize the risk of similar problems occurring in the future, it is necessary to monitor the operating conditions of the refrigerator. Regularly check the condition of the power cord and plug: they should not be twisted, kinked or damaged insulation. Dust and pet hair that accumulates in the back of the refrigerator can cause overheating of components, including relays.
It is recommended to visually inspect the rear panel of the refrigerator at least once a year. Make sure the condenser (grid at the back) is clean and the compressor itself is not covered with a thick layer of dust. Cleanliness ensures better cooling, which extends the life of not only the motor, but also the starting fittings.
⚠️ Attention: Never wash the back of the refrigerator with pressurized water or a damp cloth while the appliance is plugged in. Moisture getting on the relay contacts or compressor terminals is guaranteed to lead to a short circuit and knocking out the plugs.
It is also worth paying attention to the stability of the voltage in your network. If your lights flicker frequently or the voltage fluctuates, this will negatively affect the electronics and starting components of the refrigerator. In such cases, it is advisable to use a voltage stabilizer, which will protect expensive equipment from premature failure.
Is it possible to install a relay of a different brand?
In emergency cases, you can use universal relays, but they may work less stably and have a different resource. It is better to look for the original by catalog number.
The influence of power quality on the operation of the refrigerator
Unstable voltage in the network is another factor that is often overlooked. The starting relay is designed to operate within a certain voltage range. If the mains voltage drops below normal, the current in the motor windings increases to compensate for the loss of power. This leads to overheating of the relay and its premature failure, which ultimately causes the circuit breaker to trip.
High voltage is also dangerous: it can break through the insulation of the starting winding or cause a breakdown in the relay itself. In modern models of refrigerators, this is monitored by electronic control modules, but in older models with mechanical control, the entire load falls on the start-up protection device.
If you live in an area with an unstable power supply, regularly checking the operation of the refrigerator and the condition of its electrical components becomes part of mandatory maintenance. This will help avoid a situation where the plugs break in the middle of the night, leaving food without cold.
Why does the machine break only when the refrigerator is plugged in?
This indicates a short circuit in the circuit immediately after power is applied. Most likely, the cord insulation is broken, the plug is faulty, or a short circuit occurred inside the start relay/compressor before attempting to start the engine. A complete diagnosis of the electrical circuit of the device is required.
Is it possible to temporarily short-circuit the relay to make the refrigerator work?
Absolutely not. Excluding the starting relay from the circuit will result in the starting winding burning out in a few seconds, since it is not designed for long-term operation. This is guaranteed to completely disable the compressor.
How can you tell that it is the compressor that has burned out, and not the relay?
If a new, known-to-be-good relay does not start the engine, and a dull hum or click is heard, and the machine knocks out, most likely the problem is in the compressor (wedge or interturn). Testing the windings with a multimeter also helps: if the resistance approaches zero or infinity, the motor is faulty.
Is it dangerous to change the relay on the refrigerator yourself?
If you follow the safety rules (completely disconnecting from the network), the risk is minimal. The main danger is residual charge in capacitors (if there are electronics) or the risk of electric shock when the device is turned on. If you are not confident in your abilities, it is better to entrust the work to a professional.
How much does it cost to replace the start relay?
The cost of the part itself varies from 500 to 2000 rubles, depending on the model of the refrigerator. The work of a replacement specialist usually costs from 1000 to 2500 rubles. Self-replacement saves the cost of work, but requires time and tools.