The situation when the refrigerator stops cooling food, and the compressor either hums without starting, or clicks and goes silent, is familiar to many owners of household appliances. Often the cause of such a breakdown is the failure of the starting relay, which is responsible for starting the internal circuit engine. The question of how to turn off the refrigerator relay usually faces those who want to diagnose the unit or replace it themselves, without waiting for the technician to arrive.
Disconnecting and removing this component is the first step to restoring the unit's functionality if the problem really lies in the electrical start circuit. Start relay is a key element without which the motor-compressor will not be able to go from rest to operating mode. In this article, we will analyze in detail the algorithm of actions, safety measures and technical nuances that must be taken into account when working with the electrical equipment of a refrigeration cabinet.
Before you begin any manipulations, it is important to understand that you are dealing with electric current and refrigerant. Incorrect actions can lead to electric shock or damage to the sealed circuit. Carefully study the instructions and following the sequence of operations will help avoid additional costs for complex repairs. Next, we will look at how to correctly identify the malfunction and safely dismantle the device.
The operating principle and functions of the starting relay
The starting relay is an electromechanical device that supplies voltage to the starting winding of the compressor only at the moment it starts. As soon as the engine reaches the required speed, the relay opens the starting winding circuit, and the motor continues to operate on the main winding. This process occurs in a fraction of a second and is repeated every time the thermostat commands the cooling to turn on.
There are several types of such devices, and understanding their differences is critical for correct diagnosis. The most common are induction and posistor relays. Induction models have a movable core, which closes contacts under the influence of an electromagnetic field, and posistor models use the properties of a special material to change resistance when heated.
If the relay sticks in the closed state, the starting winding remains energized for too long, which leads to its burnout. If the contacts do not close at all, the compressor only hums, trying to turn over, but does not start. It is at this moment that the thermal protection is triggered, and the unit is turned off until it cools down.
⚠️ Attention: Continuous attempts to start a faulty compressor with a defective relay can lead to an interturn short circuit of the motor windings. If you hear a characteristic hum lasting more than 5-7 seconds, immediately unplug the refrigerator.
To understand the scale of the problem, it is worth considering the main symptoms that indicate the need to intervene in the operation of this unit. Often, users confuse a relay failure with a malfunction of the compressor itself, which leads to unnecessary replacement of an expensive unit.
- 🔊 The compressor makes a loud click, followed by a pause and a second click without starting the engine.
- 🌡️ The refrigerator compartment does not gain temperature, although the light inside is on and the fan (if any) is on. works.
- 🔥 The compressor housing or the relay mounting area gets very hot in the lower part of the refrigerator.
- ⚡ When turned on, the circuit breakers are knocked out or the fuse in the socket blows.
Diagnostics begins with a visual inspection and listening to the operation of the unit. If you notice that the engine is trying to start, but immediately stalls, the probability of a relay failure is more than 80%. However, the final verdict can be made only after dismantling and checking the element.
Preparation for dismantling and safety measures
Any work related to disassembling electrical appliances requires strict compliance with electrical safety rules. The first and most important step is to completely disconnect the refrigerator from the electrical network. It is not enough to simply turn off the button on the case, if there is one - you need to unplug the cord from the socket.
After turning off the power, you must provide access to the compressor, which is usually located in the lower rear part of the refrigerator. In some models, this requires removing the back metal cover, in others it is enough to simply move the unit away from the wall. Prepare the necessary tools in advance so as not to be distracted during the work process.
☑️ Repair tools
It is important to let the compressor cool down if it has been operating in emergency mode until now. The temperature of the casing may be high enough to cause burns or damage the plastic fasteners if touched carelessly. It is also worth checking the condition of the power cord for melting or damage to the insulation.
The workplace should be well lit. Using a flashlight will allow you to examine small details, wire markings and the condition of the contacts inside the relay. It is better to first remove dust and dirt in the compressor niche with a dry cloth or soft brush so that they do not get inside the electrical contacts during disassembly.
Do not forget about personal safety. Although there is no 220 volt voltage after unplugging, there may still be a residual charge in the capacitors of the electronics (if they are located nearby). Work carefully, avoiding touching the metal parts of the case and current-carrying elements at the same time.
If your refrigerator is under warranty, opening the seals on your own and violating the integrity of the factory fastenings may be grounds for refusal of free service. In such cases, it is more advisable to call an authorized specialist, especially if you are not confident in your abilities.
Step-by-step instructions: how to remove and disconnect the relay
The process of dismantling the starting relay is quite simple and does not require specialized education, but it does require attention to detail. Once you have secured access to the compressor and ensured there is no voltage, locate the plastic or metal box attached to the side or top of the compressor pipes.
Carefully remove the protective casing, if present. Below it you will see the compressor itself with three copper tubes and a black cylindrical capacitor, as well as a small device placed on the motor leads. This is the required relay. It can be attached with latches, screws, or simply sit tightly on the contacts.
⚠️ Attention: Do not use excessive force when removing the relay. The plastic, especially on older models, can be dry and brittle. A sharp jerk can split the device housing or damage the compressor contacts.
If the relay is held on by latches, they must be carefully pressed out with a flat-head screwdriver. If the device is simply put on the contacts, it needs to be loosened from side to side and removed, holding it with your hand. It is important to remember or photograph the position of the relay relative to the compressor terminals, since incorrect installation of the new element will lead to its immediate combustion.
The next step is to disconnect the wires going to the relay. Modern models use detachable terminals that can be removed with a slight wiggle. In older refrigerators, the wires may be soldered or twisted together. In case of soldering, you will need a soldering iron, and the twist must be carefully untwisted, having previously insulated the adjacent wires.
After disconnecting all wires, the relay can be considered completely disconnected from the system. It can now be removed from its niche for visual inspection and further inspection. Pay attention to the condition of the wires: the presence of melts, blackening or a characteristic burning smell will indicate the location of the short circuit.
The secret of marking the terminals
On most compressors, the terminals are marked with letters: C (Common) - common, S (Start) - starting, R (Run) - working. The relay is always put on in a certain orientation, which cannot be changed.
Diagnostics and performance testing
After the device is dismantled, the diagnostic stage begins. An external inspection can tell a lot about the condition of the device. If traces of soot are visible inside the case and the contacts are blackened, this is a sure sign that the device was operating in sparking and overload mode.
For a more accurate check, you need a multimeter switched to the continuity or resistance measurement mode. Check the integrity of the contacts. In normal conditions, the resistance between certain contacts should be zero or close to zero, and in other cases it should be infinite, depending on the type of relay and its position.
If you have a posistor relay, you can test it by applying voltage to it outside the refrigerator (being careful) or by measuring the resistance of the posistor. A cold posistor should have low resistance (several tens of ohms). When heated, the resistance should increase sharply. If the posistor “rings” as a short circuit or as an open circuit, it is faulty.
Induction relays are checked for core jamming. Turn the relay to different positions: if something rattles or knocks inside, it means the mechanism is broken. Also check the contacts for the presence of carbon deposits, which prevents the flow of current.
For easy comparison of the parameters of different types of faults, we present a diagnostic table:
| Type of symptom | Multimeter readings | Probable cause | Action |
|---|---|---|---|
| The compressor hums, does not start | Open circuit or high resistance | Start contacts do not close | Replacing the relay |
| Knocks out plugs when turned on | Short circuit (0 Ohm) | Sticking contacts or breakdown of the posistor | Replacing the relay |
| The refrigerator turns off after 1-2 min | Normal resistance | Faulty thermal protection or compressor | Checking the compressor |
| Clicks without buzzing | Open | Destruction of the internal elements of the relay | Replacement of the relay |
If the check showed that the relay is working, the problem may lie deeper - in the compressor itself or the wiring. However, in most cases (about 90%) the described symptoms indicate the need to replace the starting device.
Installing a new relay and assembling the system
Replacement of the faulty element is carried out in the reverse order. The purchased relay must fully match the model of your refrigerator and the type of compressor. Engine power and refrigerant type will affect the size of the relay required, so versatility is relative.
Install the new device onto the compressor terminals in the correct orientation (usually the "UP" marking should face up). Make sure the relay is seated tightly and all the way. Connect the wires to the appropriate terminals, following the diagram you photographed during disassembly, or the color coding.
Attach the protective cover and return the refrigerator to its original position. Before plugging in, visually check again that all tools have been removed and that the wires are not pinched or touching hot parts of the compressor. Plug the unit into a power outlet and listen.
The startup should go smoothly: a short sound of operation, then a smooth hum of the compressor. After 5-10 minutes, check whether the evaporator has begun to cool (usually the back wall inside the chamber or the side panels, depending on the No Frost system).
If after replacing the relay the situation has not changed, and the compressor continues to hum and turn off, the problem may be more serious. This may indicate a compressor wedge or an interturn short circuit in the windings. In this case, simply replacing the relay will not help, and a more complex repair or replacement of the motor will be required.
Common mistakes and additional recommendations
When doing their own repairs, beginners often make typical mistakes that can negate all their efforts. One of the most common is ignoring the relay orientation. Installing the device upside down or sideways (if this is not provided for by the design) will lead to incorrect operation of the mechanism and rapid failure of the new element.
Another mistake is using a relay with inappropriate parameters. Even if the connectors are the same, the current characteristics may differ. Installing a weak relay on a powerful compressor will cause it to burn out after several switching cycles. Always check the markings.
Do not forget about the cleanliness of the contacts. When installing a new relay, make sure that the terminals on the compressor itself are not oxidized. If they have a green coating or rust, they must be carefully cleaned with fine sandpaper or a file before putting on a new device.
⚠️ Attention: Never use wires to extend the relay circuit. The length of the wires from the compressor to the relay is strictly regulated by the manufacturer. Extension can change the circuit resistance and disrupt the operation of the trigger mechanism.
It is also important to take into account the age of the equipment. In very old refrigerators, the wiring may be worn out. When replacing the relay, it is recommended to inspect and, if necessary, replace the insulation of the appropriate wires to avoid short circuits in the future.
Remember that regular refrigerator maintenance, including cleaning the condenser from dust and checking the seals, reduces the load on the compressor and extends the life of the start relay. A clean heat exchanger allows the motor to operate in a gentle mode, turning on less frequently and reaching the set temperature faster.
Questions and answers about relay repair
Is it possible to repair a burnt-out relay yourself?
Theoretically, if only the posistor is burnt out or burnt out contacts, they can be replaced. However, the cost of repairs and the difficulty of selecting analogues make this idea impractical. A new relay is inexpensive and replacement takes 15 minutes. It’s easier to buy a new original or a high-quality analogue.
Why did the new relay burn out a week after replacement?
This may indicate a more serious problem with the compressor, for example, a starting wedge or a short circuit in the windings, which is why the starting currents remain abnormally high. Also, the reason may be an unstable voltage in the network or incorrect installation of the relay itself.
What is the difference between a relay for No Frost refrigerators and a regular one?
The main difference lies in the current characteristics and design adapted for specific compressor models. Although the operating principle is similar, interchangeability is not always guaranteed. It is important to select the relay according to the catalog number or the exact model of the refrigerator.
You can hear a crackling sound inside the relay during operation, but the refrigerator freezes. Is this normal?
A slight crackling sound when turning on and off (every 20-40 minutes) is normal, this is how the contacts work. But if the crackling sound is heard constantly or is accompanied by sparking, this is a sign of wear or poor contact, which requires replacement to avoid a fire.
Where to buy a suitable relay for an old refrigerator?
It is better to look for original spare parts for old models in specialized stores of spare parts for household appliances or on classifieds websites. Often universal relays with adjustable characteristics are suitable, which can be selected according to the power of the compressor.