The situation when the refrigerator stops cooling, and the compressor either hums for a few seconds and stops, or makes a characteristic click and silence, is familiar to many owners of household appliances. In 90% of such cases, the culprit of the malfunction is start-up protection relay, which is responsible for starting the engine and protecting against overloads. Starting this element is not just a “turn on” button, but a process of restoring the electrical circuit, which requires an understanding of the operating principle of the unit.
Before looking for ways to start the relay, you need to figure out why it stopped performing its functions. Most often, the problem lies in oxidation of the contacts or burnout of the heating tablet inside the case. An attempt to forcefully start the compressor without eliminating the cause can lead to burnout of the motor windings, so diagnostics must be approached with caution and the use of measuring instruments.
In this article we will examine in detail the device start-protective relay, methods for checking it with a multimeter and methods for temporarily or permanently restoring the functionality of the refrigerator. You will learn how to distinguish a relay breakdown from a malfunction of the compressor itself and what tools you will need to carry out the work safely.
Design and principle of operation of the start relay
To understand how to start the relay, you need to understand its internal structure. The start-up protection device is a plastic case, inside of which there are contacts, springs and, depending on the type, thermal protection or a start-up capacitor. The main task of the unit is to apply increased voltage to the starting winding of the compressor at the moment of start, and then turn it off when the engine reaches the required speed.
There are two main types of devices: induction (electromagnetic) and posistor. Induction relays they work due to the current passing through the coil, which creates a magnetic field and closes the contacts. PTC models use a thermistor, which is heated by current and changes its resistance, opening the circuit. Understanding the type of relay you have is critical for correct diagnosis.
It is important to note that in some models the relay is combined with a thermal release, which opens the circuit when the windings overheat. If this element fails, the compressor will not start even if the starting mechanism is working properly. Therefore, when looking for an answer to the question of how to start a relay, always check the integrity of the entire connection.
Fault symptoms and primary diagnostics
You can determine that the problem lies in the starting device by characteristic signs. If you hear a humming noise from the engine that ends abruptly with a click, followed by a pause before trying to start again, this is a classic symptom. You should also be wary of the heating of the side walls of the refrigerator in the absence of cold inside the chambers.
- 🔊 The compressor hums for 3-5 seconds, then a click is heard and there is silence.
- 🌡️ The motor gets very hot, but does not start even after cooling.
- ⚡ When connected to the network, circuit breakers are knocked out or the wiring burns out.
- 📉 The refrigerator works, but does not reach the set temperature, working non-stop.
Primary diagnostics begins with a visual inspection. Remove the back panel of the refrigerator and get to the compressor. If traces of burning, melted plastic are visible on the relay body, or the smell of burnt insulation is felt, the question of “how to start” disappears - only replacement is required. However, if there is no external damage, a more in-depth check will be required.
Often owners confuse a relay failure with a malfunction of the compressor itself. If, after removing the relay and directly applying voltage to the windings (which only an experienced technician should do), the engine does not start, then the problem is in the motor or its jam. In this case, starting the relay will not produce results.
Tools for checking and replacing the relay
To carry out high-quality diagnostics and try to resuscitate the starting device, you will need a minimum set of tools. Without them, attempts to start the relay will be in the nature of guessing on coffee grounds and can lead to false conclusions.
The main tool is multimeter (tester), which allows you to check the integrity of the circuit and resistance. You will also need screwdrivers (Phillips and flat-head) for dismantling the protective covers, pliers for carefully removing the terminals and, possibly, fine sandpaper for cleaning the contacts.
| Tool | Purpose | Importance |
|---|---|---|
| Multimeter | Measuring resistance and continuity of the circuit | Critically important |
| Screwdrivers | Removing the casing and clamps | Required |
| Pliers | Removing terminals | Advisable |
| Epaper | Cleaning oxides | By situation |
It would be a good idea to have a contact cleaning spray (Contact Cleaner) on hand, which will help remove oxides and dirt from internal surfaces. If you plan to change the device, find out the model of your refrigerator in advance in order to select a compatible analogue, since the seats and electrical parameters may differ.
Step-by-step instructions: how to remove and check the relay
The diagnostic process begins with dismantling the unit. On the back wall of the refrigerator, at the bottom, there is a compressor (black tank). A plastic box is attached to its side - this is our desired relay. It can be secured with latches or a metal bracket.
Carefully remove the fixing bracket or press out the plastic clips. Remove the relay from the compressor pins. Pay attention to the markings: the upper contacts are usually responsible for the starting winding, the lower ones for the main winding. Before checking, make sure that the device has cooled down, if there have been attempts to start it before.
Now let's move on to how to check the functionality. Turn the multimeter into resistance (ohms) mode. For posistor relays, the resistance at room temperature should be in the range of 10-60 Ohms. If the device shows infinity or zero, the element is faulty. For induction relays, the integrity of the coil and the mobility of the core are checked.
⚠️ Attention: If you see a blackened posistor inside the relay body or smell a burning smell, it will not be possible to restore its operation by cleaning the contacts. A complete replacement of the element with a new one is required.
Pay special attention to the contact group. It often happens that silvery “spots” become covered with soot. In this case, you can try to carefully clean them with an eraser or fine sandpaper, but this is a temporary measure. It is safer to replace the device, since the resource of the contact group has already been exhausted.
Starting methods: temporary solutions and replacement
If the relay is burned out, and the refrigerator is needed urgently, some craftsmen use the direct starting method, bypassing the starting device. This method is only suitable for short-term testing of the compressor or as an emergency measure for several hours, but not for continuous operation.
The essence of the method is to apply voltage directly to the starting winding at the moment of switching on. For this, a non-latching button or a special circuit is used. However, direct start deprives the motor of protection against overloads, which can quickly damage an expensive compressor.
Connection diagram for checking:Phase -> Compressor common contact
Zero -> Working winding
Button (short-term) -> Starting winding
The only correct solution on how to start a relay in the long term is to replace it. Buy a new one analog of a relaycorresponding to the power of your compressor (indicated on the nameplate, for example, 1/4 HP or 1/5 HP). Installation is carried out in the reverse order: put it on the pins, fix it with a bracket, connect the wires.
After replacement, turn on the refrigerator. If you hear the engine start confidently, there is no vibration, and after 10-15 minutes the condenser tubes (the grille at the back or sides) begin to get cold, then the repair was successful. Now the unit will operate normally.
Typical mistakes during self-repair
When trying to start the relay on their own, beginners often make mistakes that aggravate the situation. One of the most common is an attempt to “knock” on the relay or compressor during operation. This can temporarily help a stuck piston, but more often it leads to breakage of the internal tubes or damage to the motor mount.
Another mistake is ignoring the type of refrigerant and the features of the system. In modern refrigerators with inverter compressors, the classic relay may be absent altogether, and the start is controlled by an electronic module. An attempt to apply mechanical starting methods to the inverter will lead to failure of the electronics.
- 🚫 Using a relay with more power than required (will lead to underheating of the posistor and constant humming).
- 🚫 Installing the relay "upside down" (disrupts the operation of thermal protection and the mechanics of induction models).
- 🚫 Ignoring the condition of the wiring (oxidized wires will negate the operation of the new relay).
⚠️ Attention: If after replacing the relay the compressor hums but does not start, the problem may be low voltage in the network or a malfunction of the motor itself (turn-to-turn short circuit). Do not install new relays in a row - this will not help.
Also, do not forget about the cleanliness of the contacts. Even a new relay will not work if the terminals on the wires are oxidized or loose. Ensure reliable contact is the key to long service life of the equipment. If you are not confident in your abilities, it is better to entrust the diagnostics to a professional.
Prevention and extension of service life
To prevent the question of how to start the relay from arising too often, you should follow simple operating rules. The main enemy of the starting device is voltage surges and frequent on/off switching. Use a voltage stabilizer if there are surges in your network.
Regularly clean the back wall of the refrigerator from dust. A condenser clogged with dust leads to overheating of the compressor, which causes the thermal protection of the relay to operate more often, reducing its life. Also make sure that the refrigerator stands level, without distortions, which can disrupt the operation of the internal mechanics.
Timely defrosting (for No Frost systems - checking the drainage) also affects the load. If the evaporator is clogged with ice, the compressor has to work longer and harder, which increases the risk of overheating and tripping the protection. Taking care of equipment is the best prevention of breakdowns.
Remember that the life of any mechanical or electromechanical device is limited. Even the best quality relay wears out over time. If your refrigerator is more than 10 years old, keep a spare relay on hand or be prepared to quickly replace it.
How much does it cost to replace a refrigerator relay?
The cost of the start-up relay itself varies from 300 to 1500 rubles, depending on the model and manufacturer. The work of a replacement technician usually costs from 1000 to 2500 rubles, but if you replace it yourself, you save this amount.
Why does the relay click, but the refrigerator does not turn on?
The click means that the thermal protection opens the circuit due to overload. This may be caused by a jammed compressor, low voltage in the network or an interturn short circuit of the windings. The relay regularly tries to start the motor, but the protection immediately stops it.
Is it possible to close the relay directly permanently?
Theoretically, you can start the motor, but it is absolutely impossible to leave the refrigerator running without protection. If there is a jam or overload, the compressor winding will burn out, and repairs will cost the purchase of a new unit. A relay is a cheap safety element.
How to determine which relay is needed: posistor or induction?
Visually: posistor ones are usually smaller and lighter, often marked PTC. Induction ones are heavier; you can hear the knocking of the core inside when shaking. The type is also indicated in the technical documentation for the refrigerator or on the nameplate of the old relay.
The compressor is humming after replacing the relay, what's the matter?
Perhaps the relay of the wrong power or type was selected. Also, the reason may be in the compressor itself (wear of the mechanical part) or in the absence of refrigerant (freon), due to which the motor runs without load and overheats.