Sudden stoppage of the refrigeration unit often takes you by surprise, turning into a serious everyday problem. One of the most common culprits for such a breakdown is the failure of starting relay, which is responsible for starting the compressor engine. Understanding how to connect a relay from a refrigerator can save food from damage, and the owner from an expensive call to a technician.
Independent replacement of this component is quite possible for a person who knows how to handle tools and follows safety precautions. However, the process requires attention to detail, as incorrect connections can lead to permanent failure of an expensive compressor. In this article we will analyze all the stages of diagnostics, dismantling and installation of a new element.
Before taking active steps, you need to make sure that the problem lies in the starting device. Characteristic clicks, failure to start the engine when the lights are on, or overheating of the compressor housing often indicate a malfunction in the start control circuit. A competent approach to repair will allow you to restore the functionality of the equipment in the shortest possible time.
The principle of operation and types of starting relays
In order to correctly connect the relay from the refrigerator, it is important to understand its structure. This small device serves as a switch that supplies 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 device opens the circuit of the starting winding, and the engine continues to operate on the main winding.
There are two main types of such devices that are used in modern and older household appliances. Electromagnetic relays they work due to the current flowing through the main winding: when starting, the current is high, the contacts close, and when entering the mode the current drops and the contacts open. Thermal (posistor) relays use a heating element that opens the circuit when a certain temperature is reached.
Visually, these devices often look like black plastic boxes attached to the side of the compressor. The contact group and the opening mechanism are hidden inside the housing. Understanding the type of your device is critically important, since replacing an electromagnetic relay with a posistor relay (and vice versa) without changing the wiring diagram is impossible this will lead to burnout of the windings.
Some modern refrigerator models can use more complex electronic control boards, where the function of a mechanical relay is performed by a solid-state module. In such cases, diagnostics and replacement require specialized knowledge, but in most classic household refrigerators, mechanical or thermal starters are used.
⚠️ Attention: Before any manipulations with the electrical components of the refrigerator, be sure to disconnect the device from the network. A voltage of 220 volts is dangerous to life, and the capacitors in the circuit can retain a charge even after being turned off.
Diagnostics of a malfunction of the starting relay
Before looking for where to buy and how to connect the relay from the refrigerator, you should make sure that it is not working. Often the symptoms of a compressor malfunction are masked as failure of other components. Primary diagnosis begins with a visual inspection and listening to the operation of the unit.
If you hear a characteristic click, followed by the hum of the motor, and then another click and silence, this is a classic sign that the engine cannot start. At this moment, thermal protection may be triggered. If the compressor is hot and the refrigerator is not freezing, the likelihood of the starter breaking down is extremely high.
You can use a multimeter for an accurate check. It is necessary to ring the relay contacts in different positions. For a working posistor, the resistance should be within normal limits (usually several tens of Ohms), and for an electromagnetic one, the coil should ring, and the contacts at rest should be open or closed, depending on the design.
It is also worth paying attention to the appearance of the part. If traces of soot, melted plastic, or the smell of burnt insulation are visible inside the housing, then diagnostics it is complete - the element requires replacement. Do not try to restore burnt contacts, this is a temporary solution with a high risk of fire.
Tools and preparation for work
To perform a quality replacement and correctly connect the relay from the refrigerator, you need to prepare a workplace and a minimum set of tools. You don't need complex industrial equipment; a standard DIY kit is enough.
First of all, provide access to the back of the refrigerator. Move the unit away from the wall, making sure that nothing obstructs easy access to the compressor. If a protective panel (cardboard or metal) is installed on the back wall, it must be carefully removed by unscrewing the mounting screws or removing the latches.
For work you will need the following tools:
- 🔧 Screwdrivers (Phillips and flat) for removing panels and terminals.
- 🔌 Pliers or pliers for gripping wires and terminals.
- 🔦 Flashlight for good illumination of the working area in the compressor niche.
- 📸 Smartphone or camera for photographing the connection diagram before disassembly.
Pay special attention to the selection of a new part. Marking on the body of the old relay should match the markings of the new one or be its complete analogue in terms of technical characteristics. The compressor power and the type of refrigerant affect the starting current parameters, so “universal” relays are not always suitable.
☑️ Preparing to replace the relay
Process of dismantling the old one relay
Removing the faulty element is the first practical step to restoring the operation of the refrigerator. It is important to act carefully so as not to damage the compressor tubes and electrical wires, which can become brittle (brittle) from time and temperature.
First you need to remove the protective casing from the compressor itself, if equipped. Then disconnect the connectors of the wires going to the relay. In some models, the wires may be secured with terminals that must be carefully removed with pliers, without pulling the wires themselves, so as not to break them at the base.
The relay itself is usually attached to three pins coming out of the compressor housing. It is fixed either by a tight fit or by an additional bracket or clip. If there is a fixing bracket, you need to bend it. Then, rocking from side to side, carefully remove the relay from the contacts.
After removal, carefully inspect the seat on the compressor. There should be no oxides, moisture or signs of insulation breakdown. If the contacts on the compressor itself are blackened, they must be cleaned with fine sandpaper or a file before installing a new element.
Connection diagram and installation of a new relay
The most critical step is connecting the new device. The diagram of how to connect a relay from a refrigerator depends on the number of contacts and their purpose. On the body of most relays there are markings: R (Run - working winding), S (Start - starting winding) and L or an arrow (Line - power/phase).
Compare the location of the contacts on the old and new relay. Even if the models are different, the principle often remains the same: one contact goes to the network phase, the second to the working winding, the third to the starting winding. An error in the connection can lead to the compressor humming but not starting, or the winding burning out.
Below is a table of contact correspondence for common types of relays:
| Marking on the relay | Purpose of the contact | Wire color (often) | Where to connect |
|---|---|---|---|
| L / 1 / Arrow | Power input (Phase) | Brown / White | From thermostat / network |
| R / 2 | Working winding | Black / Red | Compressor contact (R) |
| S / 3 | Start winding | Blue / Green | Compressor contact (S) |
| Ground | Ground | Yellow-green | Compressor housing |
Install the new relay onto the compressor pins until it stops. Make sure it fits snugly and doesn't wobble. Then connect the wires to the appropriate terminals. If the wires are old and the insulation is cracked, it is recommended to strip the ends and, if necessary, extend them using heat shrink for insulation.
What to do if the new relay does not fit in shape?
If the purchased relay differs in the geometry of the case, but the electrical parameters are the same, you can carefully cut off the plastic fasteners of the old relay (if it is not needed for return) or use an insulating tape to secure the new device. The main thing is to ensure tight contact with the compressor terminals and the absence of vibration.
Checking operation and possible errors
After you have managed to connect the relay from the refrigerator, do not rush to remove the tool. The initial launch must be carried out under supervision. Plug in the refrigerator and listen.
The compressor should start 1-3 seconds after switching on (the posistor warm-up time). If you hear a click but do not start, or the motor hums and immediately turns off, turn off the device immediately. This may mean that the relay is selected incorrectly, or the problem is deeper (for example, the compressor itself is jammed).
Pay attention to the following signs of successful operation:
- 🔊 Smooth, monotonous hum of a running motor without knocking or vibration.
- ❄️ Gradual cooling of the evaporator inside the chamber (check after 15-20 minutes).
- 🌡️ No strong heating of the relay housing and compressor in the first minutes of operation.
If the refrigerator starts working, but after a while it turns off again, check the voltage in the network. Low voltage may prevent the compressor from developing the required power, and the thermal relay will turn it off. The reason may also be the incorrect orientation of the refrigerator - some models do not like tilting more than 40 degrees during transportation.
Frequently asked questions and troubleshooting
Even if you strictly follow the instructions, nuances may arise. Below are answers to questions that amateur craftsmen often have when replacing starting devices.
Is it possible to use a relay from another refrigerator?
You can use a relay from another model only if the electrical parameters match: compressor power (in horsepower or watts), type of refrigerant and the type of the relay itself (electromagnetic or posistor). The external shape may differ, but the landing pins must match in distance.
Why did the new relay burn out after a week?
A common reason is a jammed compressor or an interturn short circuit in the windings. In this case, the starting current remains high, the posistor overheats and is destroyed. Also, the cause may be a voltage surge in the network or poor contact in the terminal block, causing sparking.
How to distinguish a good relay from a bad one when purchasing?
It is difficult to determine quality visually. Shake the device: if something rattles inside (except for the slight sound of a posistor in some models), this is a defect. The best way is to buy original spare parts by catalog number or high-quality analogues from well-known brands (Danfoss, Secop), avoiding cheap no-name Chinese copies.
Do you need to change the capacitor along with the relay?
In most modern refrigerators with posistor relays, a separate capacitor is not used or it is built-in. If your model has an external starting capacitor (cylindrical barrel), it is advisable to check it with a capacitance tester. If it is swollen or has lost capacity, its replacement is mandatory, otherwise the new relay will not last long.
When completing the repair, make sure that all wires are laid neatly and do not touch the hot compressor tubes. Vibration during operation can wear through the insulation, leading to a short circuit. Assemble the protective casing and move the refrigerator into place, leaving a gap for ventilation.