How to choose the right starting relay for a refrigerator compressor

A sudden breakdown of a household refrigerator often causes panic, but in many cases the malfunction lies in a small and inexpensive part - the starter relay It is this component that is responsible for starting the compressor motor, providing voltage to the starting winding at the moment of switching on. If the refrigerator hums but does not start, or, conversely, turns on and immediately clicks, turning off after a few seconds, there is a high probability that this particular element needs to be replaced.

Even an inexperienced technician can independently diagnose and replace the relay, if you know what parameters to pay attention to. An error in choice can lead to repeated breakdowns or even failure of the compressor itself, which requires expensive professional intervention. In this article, we will analyze all the nuances of labeling, types of designs and an algorithm of actions that will help you find the ideal analogue for your model.

Before going to the store or placing an order online, you need to access the technical information hidden on the back wall of the unit. A correctly selected device will ensure stable operation of the motor and extend the service life of the entire refrigeration unit. Ignoring the technical characteristics is fraught with overheating of the windings and interturn short circuit.

Fault diagnosis and visual inspection

The first step before looking for a replacement is to be sure that the problem lies in the relay, and not in the compressor or thermostat itself. The symptoms of trigger failure are often similar to motor failure, so careful visual and acoustic analysis is required. If you hear a characteristic metallic click, followed by a hum lasting 1-3 seconds, and then another click and silence, this is a classic sign that the engine cannot start.

To carry out initial diagnostics, you must disconnect the refrigerator from the power supply and remove the rear protective panel. At the bottom of the unit, next to the black cylindrical compressor tank, you will see a plastic box placed directly over the motor contacts. This is the node we are looking for. Carefully disconnect it, having first photographed the wiring diagram so as not to mix up the contacts when installing a new element.

Carefully inspect the body of the removed part for traces of soot, melted plastic or swelling. Start relay often fails due to overheating or power surges in the network. If you see blackened contacts inside the case or smell a burning smell, there can be no doubt - the part requires urgent replacement. Also shake the device near your ear: if there is any debris or broken parts rattling inside, this is a sure sign of destruction of the internal mechanism.

⚠️ Attention: If, after removing the relay and visually inspecting the contacts, traces of strong soot are visible on the compressor or a burning smell comes from the motor itself, further independent actions may be dangerous. In this case, it is better to contact a professional technician to check the motor windings.

Sometimes the cause of failure is not only mechanical destruction, but also oxidation of the contact groups. Check the condition of the pins on the compressor itself: they should be clean, without green oxide deposits. If the contacts are dirty, they can be carefully cleaned with fine sandpaper before installing the new relay. The cleanliness of the connection guarantees the absence of transition resistance, which can also cause heating and false protection operations.

Types of starting relays and their design features

There are several main types of starting devices that are used in modern and old household appliances. Understanding the difference between the two is critical, as they are not always interchangeable. The most common type is induction (or posistor) relays, inside of which there is a ceramic element - a posistor. When voltage is applied, its resistance increases sharply, opening the starting circuit.

The second common type is electromagnetic relays, which operate on the principle of attraction of the core by the starting winding current. Such devices are often found in older refrigerator models and have a characteristic heavy metal body or thick plastic shell. Inside them there is a coil and a movable core, which mechanically opens the contacts after starting the engine.

• 🔹 Posistor relays - compact, lightweight, have no moving mechanical parts, operate silently, but are sensitive to shaking when cooling.

• 🔹 Electromagnetic relays - more reliable in conditions of frequent changes voltage, have a clear click during operation, but are subject to mechanical wear of the moving contacts.

• 🔹 Relay with thermal protection - are often combined in one housing with a bimetallic plate, which opens the circuit when the compressor overheats, preventing the windings from burning out.

When choosing a replacement, it is important to consider not only the type of design, but also the mounting method. Some models are attached directly to the three pins of the compressor and fixed with a spring clip, others have remote wires or special connectors. Universal relays They are rare, so you need to focus primarily on the original manufacturer's markings.

Decoding of markings and technical parameters

On the body of each starting relay there is a marking containing all the necessary information for selecting an analogue. However, manufacturers use different encoding systems, and it can be difficult to understand them the first time. The main parameter is the rated current, which is usually indicated in amperes (for example, 10A, 12A, 14A). This parameter must strictly meet the requirements of your compressor.

In addition to the current, you can find device type designations on the label or stamping of the housing. For example, letters PTC indicate a posistor type, and designations like R or RS are often found on electromagnetic models. Voltage is also important: most household relays are designed to operate in a network 220-240V frequency 50/60 Hz.

Pay attention to the location of the contacts. It can be horizontal, vertical or at an angle. Even if the electrical parameters are the same, it may be impossible to physically install a relay with a different pin angle without altering the wiring, which is not recommended. Case geometry It should allow the part to be securely fixed to the compressor without distortion.

If the markings on the body of the old relay are erased or unreadable, you will have to select an analogue based on the compressor power. For low-power motors (up to 1/4 hp), relays of 8-10 Amps are usually suitable, for medium-sized ones (1/3 hp) - 11-13 Amps, and for powerful two-compressor systems - 14-16 Amps. Exact data can be found in the refrigerator passport or on the nameplate of the motor itself.

Compatibility with compressors of different brands

Global manufacturers of compressors, such both Danfoss, Secop, Embraco, LG and Atlant, often use standardized footprints, but have their own preferences in types of protection. For example, compressors of the Danish company Danfoss (now Secop) of the BD, NL and TL series are often equipped with relays marked 101N0100 or 101N0200which are the standard of reliability.

Russian and Belarusian refrigerators (Atlant, Biryusa, Indesit of Russian assembly) are often are equipped with motors that require a relay with thermal protection built directly into the housing or placed separately on the contacts. In such models, it is important not to confuse the installation sequence: first comes the relay, then a thermal protection tablet is put on its contacts, and only then the entire structure is mounted on the compressor.

• 🔸 Compressors LG are characterized by specific connectors and a system of two relays is often used (starting and protective separately), although there are also combined units.

• 🔸 The brand Atlant uses widely used relays RTP, RTK, which have many Chinese and European analogues with similar characteristics.

• 🔸 In refrigerators Stinol i Indesit are often used relays from the company Carel or Irco, which are compact and highly sensitive.

When purchasing, pay attention to the compatibility indicated by the seller. The phrase “analogue for Danfoss” usually means that the mounting dimensions and electrical circuit are the same as the original, even if the brand of the relay manufacturer is different. Chinese copies can cost several times cheaper than the originals, but their resource is often lower, so savings here are not always justified.

⚠️ Attention: Do not try to install a relay designed for air conditioners or industrial equipment on a household refrigerator. The difference in response currents can lead to the protection not working if the piston group is jammed.

Algorithm for selecting and replacing parts

The replacement process begins with a complete blackout of the refrigerator. Unplug the power cord and move the unit away to gain access to the rear panel. Remove the cardboard or plastic cover covering the compressor area. Before touching the parts, make sure that the capacitor (if it is in the circuit) is discharged, although in modern models they are usually not in the start circuit.

Carefully remove the old relay. It can be held on a metal clip or simply sit tightly on the contacts. If there is a bracket, you need to bend it with a flat-head screwdriver. Disconnect the wires, remembering which one went where. Usually there are few of them: phase, neutral and ground. The new element is installed in the reverse order: first it is put on the compressor contacts until it stops, then it is fixed with a bracket, and only then the wires are connected.

After assembly, do not rush to close the back panel. Plug in the refrigerator and listen. Starting should happen quickly, with one confident click and transition to the smooth hum of a running engine. If you hear frequent clicks or intermittent humming, turn off the device immediately and check that the connection is correct. Perhaps the contacts are not inserted completely or are mixed up.

After making sure that it is operating normally, let the refrigerator run for 10-15 minutes in the open state, monitoring the temperature of the relay case. It may become slightly warm, but should not be so hot that it is impossible to touch. If everything is in order, install the back cover in place.

Common mistakes during selection and installation

One ​​of the most common mistakes is ignoring the orientation of the relay. Many devices are designed to operate in a strictly defined position (usually vertically, with the pins down), since they use a gravitational opening mechanism or specific cooling of the posistor. Installing such a relay sideways or upside down will result in it either not starting the motor or not turning off the starting winding, which will cause it to burn out.

Another mistake is using a relay with a lower rated current in the hope of a “safety margin”. In fact, such a relay will constantly overheat and click, turning off the refrigerator at the most inopportune moment. Thermal protection It will operate falsely, the food will begin to defrost, and the resource of the relay itself will be exhausted in a few days.

Also, technicians often forget to check condition of the wires going to the relay. Melted insulation or oxidized contacts will negate the effectiveness of the new part. If the wires are melted, they must be stripped and extended using heat-resistant cambrics. Simple twisting under conditions of vibration and heat is unacceptable.

Remember that the start relay has a limited life, and replacing it is a routine procedure for older refrigerators. Regular preventive maintenance and cleaning the condenser at the back of the refrigerator from dust will help reduce the temperature in the compressor area, which will prolong the life of both the relay and the motor itself.