The sudden cessation of operation of the refrigeration chamber or the absence of the characteristic hum of the compressor often confronts the owner with the fact of a breakdown. In most cases, the cause is a failure of the starting mechanism, which is responsible for starting the engine. It is refrigerator relay that is the very node that supplies current to the motor windings at the time of start.
Understanding where this element is located and how it functions will allow you to carry out initial diagnostics yourself. This knowledge will save time waiting for a repairman and will help you make a decision about repairs. In this article we will examine in detail the design, location and methods of testing this component.
Functional purpose and principle of operation
The starting relay is an electromechanical switch that controls the supply of voltage to the starting winding of the compressor motor. When the refrigerator is turned on, the motor rotor is stationary, and a powerful current pulse is required to spin it up. Starting device connects the starting winding for a short time, creating the necessary torque.
As soon as the engine picks up operating speed (usually this takes a fraction of a second), the current in the circuit drops. At this moment, the relay opens the contacts of the starting winding, and the engine continues to operate on the main winding. If this mechanism does not open the circuit in time, the winding may overheat and burn out. There are also thermal protection relaysthat open the circuit when the compressor overheats, preventing fire hazards.
Modern models often use solid-state options (PTC relays) that do not have moving contacts. They use a ceramic element that changes its resistance when heated by current. Such devices are considered more reliable, but their diagnosis requires an understanding of the specifics of the operation of semiconductors.
⚠️ Attention: An attempt to start the compressor without a working relay can lead to burnout of the motor windings. Never leave the refrigerator plugged in if you hear a hum, but the startup does not occur for more than 5-10 seconds.
Where is the relay in the refrigerator
The search for a faulty element begins with determining its location. In the vast majority of refrigerators, be it Indesit, Atlant or LG, the starting device is located directly on the compressor housing. The compressor is usually located in the lower rear part of the unit, hidden by a metal casing.
To get to the required part, you need to disconnect the refrigerator from the power supply and remove the rear metal panel. Under it you will see a black cylindrical or pear-shaped tank - this is the motor-compressor. At the side or lower end of its shaft there is a plastic box to which a bundle of wires fits. This is the required unit.
The fastening design may vary depending on the manufacturer. On some models, the relay simply slides onto the three pins of the compressor and is secured with a spring clip. In other cases, it may be secured with screws or plastic clips. It is important to remember exactly how the part was removed in order to correctly install a new one.
Main symptoms of a malfunction
Diagnostics begins with observing the behavior of the equipment. If you notice that the refrigerator has stopped freezing, but the light is on inside, you should listen to the sounds made by the compressor. A characteristic symptom is a cyclic repetition of startup attempts: the motor hums for a few seconds, then a click is heard, and there is silence.
This cycle can be repeated every few minutes. This indicates that the trigger mechanism is not able to close the circuit or, conversely, does not open it, which is why the thermal protection is triggered. Also, a malfunction may be indicated by:
- 🔥 Strong heating of the compressor housing or the relay itself when touched by hand.
- 💥 A characteristic smell of burning or melted plastic in the motor area.
- 🔌 Visible traces of soot or melting on the contacts upon visual inspection inspection.
- 🔊 Absence of a characteristic start-up click after being plugged in.
Sometimes the refrigerator may operate unstably, turning on and off more often than usual. This may be a sign that the contacts inside the relay are burnt and have a poor connection, which leads to a voltage drop and incorrect operation of the engine.
Why does the relay burn out?
A frequent cause of failure is not the relay itself, but wear and tear on the compressor. As the motor ages, it requires more effort to start, the current increases, and the relay cannot handle the load, burning out first. Replacing the relay in this case gives only a temporary effect.
Dismantling and visual inspection
Before picking up measuring instruments, it is necessary to remove the part for external inspection. Make sure the power cord is unplugged. Carefully remove the retaining bracket or bend the latches holding the relay housing to the compressor. Disconnect the block with wires if it cannot be removed together with the body.
During an external inspection, pay attention to the condition of the plastic. If you see blackening, melting or smell something burning, the probability of a malfunction is close to 100%. It is also worth shaking the device near your ear: if a ringing or knocking sound is heard inside, it means that the internal elements are destroyed or broken off.
For PTC relays (solid-state), a visual inspection is less informative, since there are no moving mechanical parts that can jam. However, traces of thermal effects on the contacts will be visible here too. If the case is intact and clean, proceed to the instrumental check.
Checking the relay with a multimeter
For accurate diagnostics, you will need a multimeter switched to resistance measurement mode (Ohm). The check depends on the device type. For electromagnetic relays, it is necessary to ring the coil winding. The resistance of a working coil is usually from 30 to 200 Ohms, depending on the model.
If the multimeter shows infinity (open) or zero (short circuit), the coil is faulty. You should also check the contacts for short circuits. In the normal position (vertically, as on a compressor), the contacts of the starting winding should be open. If you put the relay on its side, the contacts should close with a characteristic click, and the device will show a resistance close to zero.
PTC elements are checked by measuring the resistance between the contacts. At room temperature, a serviceable element has a certain resistance (usually several tens of ohms). If the device shows an open circuit or the resistance differs significantly from the nominal value, the part requires replacement. Important: after checking by heating, the PTC element needs time (about 5 minutes) to cool down in order to begin conducting current again.
☑️ Test algorithm with a multimeter
Table of typical faults
Systematization of data helps to make a diagnosis faster. Below is a table linking symptoms with probable causes of relay failure.
| Symptom | Probable cause in the relay | Action |
|---|---|---|
| Buzzes and clicks, does not start | Breakage of the starting winding or coil | Replacing the relay |
| The compressor hums and turns off | Stuck contacts or PTC malfunction | Replacing the relay |
| The refrigerator does not turn on at all | Open circuit of the thermal protection | Check with a tester |
| A crackling sound is heard inside the relay | Destruction of internal elements | Urgent replacement |
| Burning smell | Overheating of contacts | Replacing the relay and checking the compressor |
It is worth noting that even if testing with a multimeter shows normal resistance values, the relay may not operate correctly under load. Mechanical wear or loss of magnetic properties may not be visible on the instrument. Therefore, if the symptoms indicate a breakdown, and the relay is old, replacing it is the most rational solution.
Replacement and selection of analogues
If diagnostics have confirmed a malfunction, you need to purchase a new part. Relays are selected strictly according to the markings indicated on the body of the old device, or according to the power and type of compressor. There are no universal solutions, since the current characteristics of different motors are different.
The installation process is simple: the new part is put on the compressor pins in the same position in which the old one was (usually the “UP” arrow should face up). Then the wires are connected and the protective bracket is fixed. After assembly, turn on the refrigerator and listen: the startup should be quiet, without buzzing or clicking.
⚠️ Attention: Technical specifications of compressors and relay compatibility may change by manufacturers. Before purchasing a new part, check the markings with the official spare parts catalog for your refrigerator model.
Frequently asked questions (FAQ)
Is it possible to start a refrigerator without relay?
Theoretically, you can start the engine by applying current directly, but this is extremely dangerous and is not recommended. Without a starting device, the compressor will not be able to gain speed and will burn out in a matter of seconds, or will blow out the automatic fuse in the panel.
How much does it cost to replace the relay?
The cost of the part itself varies from 500 to 2000 rubles, depending on the brand and type. The work of a replacement technician usually costs from 1000 rubles, but independent replacement takes no more than 15 minutes.
Why does a new relay burn out immediately after installation?
This is a sure sign of a malfunction of the compressor itself. If the motor is “heavy” (turn-to-turn short circuit, mechanical wear), it consumes too much starting current, which melts the contacts of the new relay. In this case, the compressor needs to be replaced.
Where to buy an original relay?
It is better to look for original spare parts in specialized stores of spare parts for household appliances or from official dealers of the brand of your refrigerator. Markets often sell universal Chinese analogues, the service life of which may be lower.