A sudden stop of the compressor or a characteristic click, after which the refrigerator stops cooling, often signals a failure of the start relay. This small but critical element is responsible for starting the engine and operating it normally. If you notice that the engine hums but does not start, or turns on for just a couple of seconds and stalls, most likely the problem lies in this unit.
Ignoring the symptoms can lead to more serious consequences, even burning out the compressor windings. Understanding the causes of relay burnout will help not only eliminate the malfunction, but also prevent the situation from reoccurring in the future. In this article we will analyze in detail the structure of the mechanism, the main risk factors and the algorithm of actions when a breakdown is detected.
The principle of operation and the design of the starting relay
To understand why the starting relay burns out, you need to understand its functional purpose. This component is an electromechanical switch that supplies current to the compressor's starting winding only when it starts. As soon as the motor rotor reaches the required speed, the relay opens the circuit and the motor continues to operate on the main winding. Some models also have built-in thermal protection that turns off the power when overheated.
Structurally, the device can be current or posistor. In the first case, an electromagnetic coil is used, which opens the contacts when a certain current is reached. In the second, there is a temperature-sensitive element (posistor), which changes its resistance when heated. Inverter refrigerators may have a more complex electronic control circuit, but the principle of protection remains similar.
⚠️ Attention: An attempt to start the compressor directly, bypassing the relay, can lead to instant burnout starting winding of the motor due to the lack of phase shift or protection.
The key element is the contact group, which experiences maximum load at the moment of switching on. This is where sparking most often occurs, leading to burnt contacts. Also an important role is played by a thermal relay, which should operate when the permissible temperature is exceeded, protecting the motor from overheating.
What is the difference between a current and a posistor relay?
A current relay uses current to open the contacts: while the current is high (start), the contacts are closed. The posistor relay is heated by current and increases resistance, opening the circuit. PTC resistors are considered more reliable and modern, since they do not have moving mechanical parts inside the switch itself.
Main reasons for relay burnout
There are several fundamental reasons why a part fails. Most often, the culprit is natural wear of the contact group. Every time you turn on the refrigerator, an electric arc jumps between the contacts, which gradually burns out the metal. Over time, the gap increases, the resistance increases, and the part begins to heat up, which ultimately leads to complete failure.
The second common reason is power surges. Short-term surges or, conversely, prolonged low voltage cause the relay to operate in abnormal mode. If the voltage is not enough to reliably start the motor, the contacts may remain closed longer than expected, causing overheating and melting of the housing.
- 🔥 Overheating of the housing The compressor transmitted to the relay mounted on top accelerates the degradation of internal components.
- ⚡ Frequent power outages lead to cyclic restarts of the engine, which wears out the mechanics of the switch.
- 💧 Moisture or condensation on the contacts causes corrosion and a short circuit inside the device.
Manufacturing defects cannot be ruled out, especially in budget models of household appliances. The use of cheap materials with a low melting point leads to the fact that the body is deformed at the first serious loads. In such cases melting of the plastic case occurs even without obvious power surges, simply from normal, but intensive work.
The influence of problems with the compressor on the relay
Often the question “why the starting relay burns out” hides more a deep problem with the engine itself. If the compressor has mechanical damage, jammed pistons or an exhausted service life, the current in its windings increases many times over. The relay, trying to start a “heavy” motor, works at the limit of its capabilities and quickly fails.
Replacing the relay in this case will only give a temporary effect. The new device will burn out in a few hours or days, since the reason lies not in the electrics, but in the mechanics of the refrigeration unit. Therefore, before installing a new part, it is recommended to diagnose the condition of the compressor by measuring the resistance of the windings.
It is also worth considering the condition of the wiring going from the relay to the compressor. Oxidized terminals or damaged insulation create additional resistance. This leads to local heating at the junction, which negatively affects the operation of the entire starting system. Visual inspection of the wires often helps to identify blackening or traces of melting.
Fault symptoms and diagnostics
You can determine that the relay has failed by its characteristic signs. The most obvious symptom is that the refrigerator hums, but does not start. After a few seconds, a click is heard, the humming stops, and after a while the cycle repeats. This is thermal protection, turning off the power to avoid a fire.
Another sign may be a complete lack of response from the equipment when it is plugged in, although the light in the chamber is on. In some cases, a faulty relay may “stick” when turned on, causing the compressor to operate continuously without turning off, which leads to freezing of food and excessive energy consumption.
For accurate diagnosis, it is necessary to remove the part and inspect it visually. The presence of carbon deposits, cracks on the body or a burning smell clearly indicates the need for replacement. If there are no external signs, you will need a multimeter to “test” the contacts and check the resistance.
| Symptom | Probable cause | Actions |
|---|---|---|
| Clicks, the motor does not start | Open circuit or sticking contacts | Replacing the relay |
| The compressor is hot, does not work | Thermal protection has tripped | Checking the motor windings |
| The refrigerator does not turn off | Contacts are welded (closed) | Urgent replacement of part |
| Smell of burning in the rear | Melting of insulation or housing | Inspection of wiring and relays |
The process of replacing the start relay
Replacing a burnt out element is a procedure that can be done with your own hands if you have basic skills. The first step should always be to completely unplug the refrigerator. Safety comes first, so do not neglect this rule, even if it seems that the current in the rear of the unit is not dangerous.
Next, you need to remove the protective casing at the bottom of the refrigerator where the compressor is located. The relay is usually placed directly on the compressor rod and secured with a bracket or plastic latches. By carefully disconnecting the wires (after photographing their location), you can remove the faulty part.
- 🛠️ Take a photo of the wire connection diagram before dismantling so as not to confuse the contacts during assembly.
- 🧹 Clean the installation site from dust and cobwebs to ensure better heat dissipation.
- 🔌 Make sure that the new part is identically marked and fits your compressor model.
Installing the new relay is done in the reverse order. It is important to make sure that it fits tightly and clicks, and that the wires do not touch hot parts of the compressor or sharp edges of the housing. After assembly, turn on the refrigerator and listen: the startup should be quiet, without crackling or repeated clicks.
☑️ Checklist before replacing the relay
Prevention and extension of service life
In order not to encounter the problem of replacing the relay, you should follow simple operating rules. First of all, make sure your refrigerator has good ventilation. The back wall should not fit tightly against the wall or furniture, otherwise the heat dissipation is disrupted, and all components operate at elevated temperatures.
Using a voltage stabilizer is another effective way to protect electronics and starting equipment. This is especially true for private houses and summer cottages, where the quality of the electrical network often leaves much to be desired. Stable voltage prolongs the life of not only the relay, but also the compressor as a whole.
⚠️ Attention: Do not install the refrigerator near heating appliances or in direct sunlight. Increased ambient ambient temperature is the main enemy of starting equipment.
Regular cleaning in the compressor area will also not be superfluous. A thick layer of dust acts as a heat insulator, preventing the parts from cooling. Wipe the radiator grille and the compressor itself with a dry cloth at least once every six months. This simple action will help maintain optimal operating temperature conditions.
Frequently asked questions (FAQ)
Is it possible to temporarily start a refrigerator without a relay?
Technically, you can start the motor by closing the contacts directly, but doing this is strictly not recommended. Without a relay, the compressor will work on only one winding, will not reach full power and will burn out after a short time due to overheating. This is an emergency measure only for diagnostics, but not for operation.
A burnt relay affects electricity consumption?
Yes, if the relay is faulty (for example, the contacts burn and the resistance increases), the refrigerator may consume more energy. Also, with frequent unsuccessful startup attempts (clicking), electricity consumption increases, although no cold enters the chamber.
How to choose an analogue if the original is not on sale?
You need to look at the markings of the relay itself and the compressor. Key parameters: motor power (watts or horsepower), refrigerant type (R134a, R600a) and relay type (current/positor). Universal relays often have a power switch, which simplifies selection.
Why does a new relay burn out immediately after installation?
This indicates that the cause of the breakdown has not been eliminated. Most likely, the compressor itself is faulty (interturn short circuit, wedge) or critical voltage surges are observed in the network. An in-depth diagnosis of the unit and the electrical network is required.