A sudden stop of the compressor or a characteristic clicking sound, after which the refrigerator stops freezing, often indicates a failure of the start-up relay. This small but critical element is responsible for starting the motor and protecting the windings from overloads. Without it, full-fledged operation of the refrigeration unit is impossible, so the issue of replacement arises sharply before the owner of the equipment.
Independent selection of relays is a solvable task, but requires attention to detail. An error in choosing the type or characteristics can lead to re-combustion of the part or, worse, to failure of the compressor itself. In this article we will analyze all the nuances of marking, design features and an algorithm of actions that will allow you to accurately find the spare part you need.
Before going to the store or placing an order online, it is necessary to carry out initial diagnostics and dismantling. Do not rush to buy the first part you come across with a similar appearance, since starting relay this is a high-precision mechanism, the parameters of which strictly correspond to a specific engine.
Diagnostics and causes of relay malfunction
Understanding why the old one failed The device will help avoid a repeat of the situation. Most often, failure occurs due to natural wear of contacts or overheating of the bimetallic plate. If the compressor hums but does not start, and after a few seconds a click is heard and the motor goes silent, this is a sure sign of a problem in the starting circuit.
In some cases, it is not the relay itself that is to blame, but the condition of the electrical network or the compressor itself. For example, low line voltage may prevent normal starting, causing the protective mechanism to operate continuously. It is also worth checking whether the motor is mechanically jammed, since in this case replacing the relay will only give a short-term effect. piston group motor, since in this case replacing the relay will only give a short-term effect.
Visual inspection of the removed part often provides more information than external symptoms. If traces of burning, melted plastic or oxidized contacts are visible inside the case, then the element definitely requires replacement. Sometimes it is enough to simply clean the contacts, but if bimetallic plate is deformed, repair is impossible.
- 🔌 Characteristic frequent clicking when trying to start the motor.
- 🌡️ Strong heating of the compressor housing when the refrigerator is not working.
- 📉 The voltage drop in the network is below the permissible threshold (less than 190 V).
- 🔥 The presence of the smell of burnt insulation in the compressor area.
⚠️ Attention: If after replacing the relay the compressor does not start again or immediately knocks out the machine panel, stop trying to turn it on immediately. This may indicate an interturn short circuit in the motor windings, which requires replacing the compressor.
Diagnostics must be comprehensive. Do not ignore winding resistance measurements with a multimeter if you have the appropriate skills. The resistance of the starting winding is usually higher than the working winding, and this ratio must be maintained. Violation of these parameters indicates a deeper problem that a simple relay will not solve.
Types of start-up relays for refrigerators
All relays are divided into several main types depending on the principle of operation and design. Understanding the difference between the two is critical, as they are not always interchangeable. The main types are induction, posistor and thermal relays.
Induction relays work due to electromagnetic induction. At the moment of starting, the current in the starting winding is high, and the magnetic field lifts the core, closing the contacts. When the motor picks up speed, the current drops, and the core opens the circuit under its own weight. Such devices are sensitive to spatial position.
Posistor (thermal) relays use the property of a semiconductor element (posistor) to sharply increase resistance when heated. When voltage is applied, the posistor is cold and passes current, starting the engine. Heating up from the passing current, it breaks the starting winding circuit. These models are less sensitive to position, but require time to cool down before restarting.
There are also combined devices that combine start-up and protection functions. They can have a complex design with several contacts and leads. When selecting, it is important to take into account not only the principle of operation, but also the number of contacts, as well as their location on the body.
Marking and decoding of designations
The key stage of selection is reading the markings. An alphanumeric code is printed on the body of each relay, which contains all the necessary information. Ignoring these symbols often leads to purchasing the wrong part.
The first letter in the marking usually indicates the type of device. For example, the letter P means “relay”. The second letter specifies the purpose: T —thermal, P —starting, Z —protective. Combinations like RTK or RTP are standard for many Soviet and post-Soviet refrigerators.
The numbers following the letters indicate the modification, current range or specific series. For example, in marking RTK-1-3 number 1 may indicate the type of design, and 3 may indicate the permissible current. For imported models, their own encoding system is used, often tied to the compressor brand.
Below is a table of common markings and their compatibility with compressor types:
| Relay marking | Type devices | Applicability | Features |
|---|---|---|---|
| RTK (1, 2, 3...) | Starting protection | K series compressors (KD, KDM) | Requires strictly vertical installation |
| RTP (1, 2, 3...) | Start-protective | P series compressors (PB, PD) | Posistor principle actions |
| RPU (1, 2...) | Protective | Universal | Protection only, without starting |
| MCI (1, 2...) | Start-protective | Imported and new models | Compact size |
Pay attention to the current characteristics. If the relay says 1.2-1.6 A, and you install a part with a range 2.0-2.5 A, the protection may not work in time and the engine will burn out. An exact match or being within the acceptable range is a prerequisite.
Algorithm for selection and dismantling of the part
For successful replacement, you must act consistently. First, unplug your refrigerator. Remove the rear protective panel at the bottom of the unit to gain access to the compressor. This often requires a Phillips screwdriver.
Carefully remove the old relay. It can simply be put on the three contacts of the compressor or fixed with a metal bracket. If a staple is used, it must be pressed out. Do not pull sharply so as not to damage the suitable wires.
☑️ Checklist before purchasing a new relay
Compare the removed part with the new one. They must be identical in shape, contact arrangement and markings. Pay special attention to the orientation: some relays can only be installed in one position, which is indicated by an arrow UP or Top on the body.
If you have not found an exact analogue by marking, you can use universal relays. They are equipped with a set of adapters for different types of compressors. However, this option is considered a temporary solution, since the reliability of protection in universal models is often lower than in the original ones.
⚠️ Attention: Before installing a new relay, make sure that the contacts on the compressor itself are not oxidized or burnt. If necessary, clean them with fine sandpaper or a file to ensure quality contact.
When connecting wires, follow the color markings, if any. If the wires are mixed up, the compressor may hum, but not start, or immediately go into protection. In difficult cases, it is better to sketch out the connection diagram before dismantling.
Compatibility with brands and models
Different refrigerator manufacturers use compressors of different brands, which affects the choice of relay. For example, in refrigerators Atlant there are often relays of the RTK or RTPseries, which are interchangeable within the same series of compressors. In technology Indesit i Ariston Italian compressors Aspera with relay PTM or R6.
Refrigerators LG and Samsung can be equipped with compressors of their own production or from LG, where specific relays with three or four contacts are used. Here it is important not to confuse the starting and protective devices if they are made separately.
Secrets of compatibility of Chinese compressors
Chinese compressors (QD, Jiaxing, etc.) often have a standard pinout, similar to the Soviet models of the K series. However, their current characteristics may differ. Always check the amperage indicated on the compressor nameplate with the relay range.
For old models of refrigerators ZIL or Minsk it is difficult to find original relays, but they are successfully replaced with modern analogues, such as RTK-1-3 instead RTK-1-1, if the installation space allows. The main thing is compliance with the cutoff current.
In modern inverter refrigerators, classic starting relays can absent, since engine starting is controlled by an electronic unit. In such cases, “clicking” sounds and starting problems may indicate a faulty control board rather than a mechanical relay.
Installation and testing after replacement
Once the new relay has been selected and prepared, its installation takes a few minutes. Push the device onto the compressor contacts until it stops. If the design provides, secure it with a metal strip or bracket.
Connect the wires to the appropriate terminals. Make sure the connection is tight and the wires are not loose. The vibration of a running compressor can loosen a poor connection, leading to sparking and heating.
Put the back panel in place and secure it with screws. Plug in the refrigerator. Normal operation is characterized by a smooth hum of the motor and subsequent cooling of the chambers. If after 10-15 minutes of operation the relay does not click and does not turn off the motor, and the refrigerator freezes, the replacement was successful.
In the first hours after the replacement, monitor the temperature of the relay housing. It may become slightly warm, but should not be so hot that it is impossible to touch. Excessive heating indicates an incorrect selection of the current range.
Frequently asked questions (FAQ)
Is it possible to install a relay with a large current range if there is no exact analogue?
It is strictly not recommended. If the cut-off current is too high, the relay will not break the starting winding circuit in time, which will lead to its burnout. A minimal excess is allowed (up to 0.1 A), but it is better to look for an exact analogue.
Why does a new relay burn out immediately after installation?
There may be several reasons: a jammed compressor (the motor cannot turn), a short circuit in the motor windings, or a malfunction in the electrical circuit of the refrigerator. It is also possible that the relay was initially defective or did not match the type.
What is the difference between the RTK and RTP relays?
RTK is a relay with an inductor, sensitive to position (works only vertically). RTP is a posistor (thermal) relay, which is less demanding in terms of orientation, but requires time to cool down (3-5 minutes) before restarting.
How to understand that the relay is “stuck”?
If the contacts inside the relay are welded or stuck in the closed state, the starting winding remains energized constantly. This causes a strong hum, heating of the compressor and eventual combustion of the windings. You can check with a multimeter: in a cold state, the contacts of the starting circuit should open in a vertical position (for RTK).
Do you need to lubricate the relay contacts with graphite?
No, modern relays do not require lubrication. The entry of foreign substances may disrupt the operation of the mechanism or cause sparking. If the contacts are oxidized, it is better to carefully clean them, but if the part is severely worn, it is easier to replace it.