A sudden stop of the compressor or the refusal of the refrigerator to turn on often signals a failure of the start-up relay. This small but critical element is responsible for starting the engine and protecting against overloads, and its failure can lead to burnout of the compressor windings. Owners of household appliances often face difficulties when finding a replacement, since markings on parts can be erased, and the range in stores is wide and varied.
A correctly selected relay ensures stable operation of the refrigeration unit, extends the life of the compressor and guarantees safe operation. An error in choice can lead to the refrigerator stopping freezing, and the new compressor failing in a matter of hours. In this article, we will look at how to accurately determine the type of malfunction, decipher manufacturer codes and select a compatible analogue without contacting a service center.
First, you need to make sure that the problem lies in the relay, and not in the compressor or thermostat itself. Often the symptoms are similar: engine humming, clicking, lack of cold. Diagnostics begins with a visual inspection and “tapping” the part. If you hear a ringing sound when you shake it lightly, it means that the trigger mechanism or contacts inside are damaged and require immediate replacement.
Diagnostics of a faulty start-up relay
Before going to the store for spare parts, you need to remove the relay and carry out a thorough inspection check. This process requires compliance with safety precautions, since the work is carried out with electrical components. The first step should always be to completely unplug the refrigerator. Only after this can you begin to dismantle the compressor casing and remove the relay itself.
Visual inspection often provides more information than it seems at first glance. Pay attention to the condition of the plastic case: if it is melted, blackened or has traces of sparking, the part is definitely faulty. Also check the contacts for oxidation and carbon deposits. Thermal relay may look intact on the outside, but inside the bimetallic plate could have lost its properties.
⚠️ Attention: If when connecting a new relay, the compressor hums, but does not start, and after a few seconds a click is heard shutdown - stop testing immediately. This is a sign of a jammed compressor or an interturn short circuit, and further switching on can finish off the motor.
Checking the integrity of the inductor and contacts is done using a multimeter. The resistance of the windings must correspond to the passport data, and the contacts in normal condition should “ring” or open depending on the type of relay. For induction relays the contacts open at rest, while posistor ones behave differently.
- 🔍 Shake the relay near your ear: the presence of rattling indicates destruction of the internal mechanism or a broken part.
- 🔥 Inspect the contacts for carbon deposits, melting or changes in the color of the metal.
- ⚡ Test the windings and contacts in different positions (vertical and horizontal) with a multimeter.
If there are no visual defects, but the refrigerator does not work, the problem may be in the thermal release, which does not operate on time or, on the contrary, it opens the circuit prematurely. In such cases, replacing the relay often solves the problem, but requires precise selection according to the current characteristics.
Types of starting relays and their design features
Understanding the operating principle of various types of relays is the key to successfully selecting a replacement. In household refrigerators, three main types of devices are most often found: induction, posistor and relays with thermal release. Each of them has its own design features and installation requirements.
Induction relays work on the principle of an electromagnetic field. When voltage is applied, current passes through the coil, creating a magnetic field that draws in the core and closes the trigger contacts. As soon as the motor rotor picks up speed, the current drops and the contacts open. Such relays are sensitive to position in space and are often marked “UP” or an arrow pointing up.
Posistor relays (PTC) are more modern and have no moving mechanical parts. Inside them there is a thermistor, which, when heated by current, sharply increases its resistance, actually breaking the starting winding circuit. They are less sensitive to position, but are afraid of moisture and shock. After operation, they require time to cool down (usually 1-2 minutes) before starting again.
What is the danger of installing a posistor instead of an induction relay?
Replacing one type with another is possible only if you have the appropriate documentation. Induction relays open the circuit when the current drops, and posistors open the circuit when they heat up. If you place a posistor in a circuit designed for an induction relay without modifications, the engine may not reach operating mode or may burn out due to the fact that the starting winding remains on for too long.
Thermal protection is often built into the relay housing or attached directly to the compressor. It is a bimetallic plate that bends when heated and opens the power circuit. Operation current The thermal relay must strictly correspond to the rated current of the compressor, otherwise the protection will be false or ineffective.
| Relay type | Operation principle | Position sensitivity | Recovery time |
|---|---|---|---|
| Induction | Electromagnetic retraction | High (requires orientation) | Instant |
| Posistor (PTC) | Thermistor heating | Low | 60-120 seconds |
| Thermal | Bimetal bending | Average | Depends on cooling |
| Comparative characteristics of the main types of starting devices | |||
When choosing an analogue, it is important to consider not only the type, but also the method of fastening the contacts. Some refrigerator models use specific connectors that may not match their universal counterparts. In such cases, a slight modification of the contact group or the use of adapters may be required.
Deciphering markings and searching for analogues
The most reliable way to select a relay is to find its original article number. It is usually applied to the body of the part by laser engraving or stamping. However, over time, markings may fade, become unreadable, or be completely destroyed due to overheating. In such cases, you have to look for analogues by parameters.
The key parameters for the search are rated current the compressor and the type of refrigerant (although the latter rather affects the compressor itself). The current is specified in amperes (for example, 1/4 HP, 1/5 HP, or a specific value in Amps). It is also important to pay attention to the mains voltage (220V or 110V), although in 220V relays the input is often universal, the output part may differ.
Manufacturers use different coding systems. For example, relays Danfoss (now Secop) have their own designation system, different from Indesit or Atlant. Universal relays often have a compatibility chart on the packaging, which lists the compressor models. If you do not find an exact match, you can use cross-tabulations of manufacturers.
⚠️ Attention: Do not use relays with a current range significantly exceeding the rating of your compressor. Thermal protection may not operate in time, which will lead to overheating of the windings and costly repairs.
In some cases, compatibility codes with other brands are indicated on the relay housing. For example, relays RT series can be interchangeable with R600 series under certain conditions. Always check the connection diagram: the number of contacts and their location must match.
If the markings are completely missing, you will have to measure the compressor current with current clamps at the time of start-up (this is difficult to do without experience) or select a relay by elimination, starting with the most common models for a given refrigerator displacement. However, this approach carries risks.
Compatibility table of popular brands
To simplify the search for a replacement, we present a correspondence table for relays from popular manufacturers. Please note that this is reference data, and before purchasing it is recommended to check the appearance and fit dimensions.
| Original (Brand) | Series / Model | Possible analogue | Compressor type |
|---|---|---|---|
| Atlant | RTP-0, 12, 13, 14 | Indesit, Ariston (compatible) | Piston |
| Danfoss / Secop | 101N0011, 101N0021 | Universal PTC (18-25 Ohm) | Piston |
| LG | PTC Relay (various codes) | Universal posistor | Piston |
| Whirlpool | Start Relay (W series) | Specific (rarely universal) | Piston |
| Approximate correspondence of starting relays for various brands of refrigerators | |||
It is worth noting that conventional relays are not suitable for inverter compressors. Inverters use electronic control modules, and an attempt to install a mechanical relay will lead to breakdown of expensive electronics. Inverter systems require diagnostics through the service mode and replacement of the control board.
When purchasing a universal relay, carefully study the package. Often the kit includes additional adapter blocks and wires that allow you to adapt the relay to different types of connectors. This makes universal kits popular among craftsmen.
If your compressor is not in the table, look for its model on the Internet along with the word “relay replacement” or “relay replacement”. Repair forums often contain up-to-date information about which relays were installed instead of the original ones in specific refrigerator models.
☑️ Check before purchasing a relay
Step-by-step instructions for replacing the relay
Replacing the start-protection relay - a procedure that is accessible even to a beginner, if you follow care and safety precautions. The main rule: take your time and do not use excessive force, as ceramic and plastic parts are fragile.
First remove the back cover of the refrigerator (cardboard or metal) to gain access to the compressor. Disconnect the terminal block, if present, and carefully remove the old relay. It may fit tightly, so rock it slightly from side to side. Thermal protection Can be mounted separately or be part of a single unit.
Install the new relay, observing the orientation (top-bottom). Connect the wires in the same order as they were on the old relay. If the connectors do not match, use the adapter from the kit or carefully re-solder the contacts, observing the polarity and cross-section of the wires.
⚠️ Attention: When installing, make sure that the wires do not touch the hot compressor tubes or moving parts. The insulation of the wires must be intact, otherwise a short circuit may occur.
After installation, secure the relay to the compressor (if there is a lock) and put on the protective cover. Plug in the refrigerator and listen. Startup should be smooth, without buzzing or clicking. After 10-15 minutes, check whether the evaporator begins to get colder.
If after replacing the refrigerator started working, but after a while it turned off again, perhaps the problem is not only in the relay. Check the capacitor (if there is one in the circuit) and the condition of the compressor windings. Sometimes an old relay burns out due to problems with the motor itself.
Frequent errors during selection and installation
One of the most common mistakes is ignoring the type of compressor. An attempt to install a relay from a conventional refrigerator on a unit with inverter control or a second generation compressor (for example, some LG or Samsung models) is doomed to failure. Such systems require specific starting currents.
Another error is the incorrect orientation of the relay in space. Induction relays only operate in a certain position, indicated by the arrow. If you turn such a device over, the core will not be able to fall under the influence of gravity, and the starting winding will not turn off, which will lead to humming and overheating.
Using a relay with a large contact gap or, conversely, with stuck contacts is a common cause of repeated breakdowns. The gap between the contacts in induction relays must be strictly definedto ensure timely opening of the circuit when the speed increases engine.
Is it possible to clean the contacts of an old relay?
Theoretically, you can clean the contacts with fine sandpaper if they are simply burnt. However, this is a temporary measure. The springing properties of the bimetallic plate and the strength of the magnet are lost over time, and after a couple of weeks the relay will fail again. It is better to replace the entire part.
Also, do not forget about the capacitor, if it is present in the circuit. An old, dried-out capacitor may not provide enough capacity to start, and even a new, working relay will not help start the compressor. Always check the entire starting circuit as a whole.
In conclusion, choosing the right relay is the key to the long life of your refrigerator. Do not skimp on this part, choose trusted manufacturers and carefully check compatibility before installation.
Can a universal relay be used for any refrigerator?
Universal relays are suitable for many models, but not all. It is important to check the current range, compressor type (piston) and physical compatibility of the mountings. For specific models (for example, with two compressors or a special starting system), original spare parts may be required.
Why does a new relay burn out immediately after installation?
This may indicate a malfunction of the compressor itself (interturn short circuit, jamming), problems with the capacitor, or incorrect selection of the current characteristics of the relay. Also, the cause may be a voltage surge in the network.
How to distinguish a posistor relay from an induction one?
A posistor relay is usually lighter, has no moving parts (does not rattle when shaken) and is often made in a black plastic case of a cylindrical or rectangular shape. An induction relay is heavier, contains a copper coil and a movable core.
Do the relay contacts need to be lubricated?
No, the contacts cannot be lubricated. This will lead to carbon deposits, poor contact and eventual burnout of the relay. The contacts must be dry and clean.