Modern refrigerator is a complex unit, where each node performs a critical function, ensuring the safety of products. Often the cause of a sudden breakdown is not the compressor itself, but a small but vital element - the start relay. It is responsible for starting the engine and protecting against overloads, opening the circuit during power surges or jamming of the piston group.
If you notice that your Indesit, Atlant or LG has stopped freezing, and the motor hums for just a few seconds and clicks, trying to start, most likely the problem lies in the contact group. Independent Replacing the relay is a procedure quite accessible to a home handyman who has basic electrical skills and a minimal set of tools. However, haste here is unacceptable, since an error in the connection can lead to burnout of the motor windings.
Before proceeding with disassembly, you must completely disconnect the appliance from the power supply. Even briefly touching live parts can be life-threatening. Next, you should remove the rear protective panel at the bottom of the case to gain access to the compressor, where the required element is usually secured.
In this guide we will examine in detail the design of various types of triggers, the algorithm for diagnosing them and the correct sequence of actions when installing a new part. It is important to understand that different manufacturers use different types of fastenings and connection diagrams, so there is no universal method, but the general principles remain unchanged.
Principle of operation and types of starting relays
The main task of this device is to briefly supply voltage to the starting winding of the electric motor, which creates the necessary torque. As soon as the rotor picks up speed, the starting winding must be disconnected, otherwise the motor will burn out. Depending on the design, this process can be implemented in different ways.
The most common induction (electromagnetic) relays, which are widely used in old models of Soviet refrigerators and some modern budget series. They are based on a coil connected in series to the working winding circuit. When starting, the current is high, the magnetic field draws in the core, closing the contacts of the starting winding. When the speed increases, the current drops and the spring opens the contacts.
The second common type is thermal (RTK), which are often combined with induction. It uses a bimetallic plate, which bends when heated by current and opens the circuit. There are also electronic options that are more reliable, but more difficult to diagnose without special equipment. Understanding your relay type is the first step to a successful repair.
⚠️ Warning: Never attempt to operate a refrigerator with a stuck or disassembled relay. This can lead to a wiring fire or irreversible damage to the compressor due to operation only on the working winding.
What is the difference between the RTP and RTK relays?
The RTP (starting) relay usually has a vertical contact arrangement and works only to close the starting winding. The RTK (start-up protection) relay combines the functions of start-up and thermal protection, often has a horizontal arrangement and a more complex internal circuit with a bimetallic plate.
Diagnostics of faults before replacement
Before buying a new part, you need to make sure that the problem is in it and not in the compressor. A visual inspection often provides the first clues: blackened plastic, melted contacts or a characteristic burning smell indicate a breakdown. If there are no external signs, you will need a multimeter.
To check, remove the relay from the compressor and inspect the insides. In induction models, the core must move freely inside the coil without jamming. Check the integrity of the coil winding with a tester - the resistance should be within normal limits (usually several tens of Ohms), and not broken.
Pay special attention to the contact group. Carbon deposits on the contacts increase resistance, which leads to a voltage drop and the inability to start the engine. Sometimes it is enough to clean the contacts with fine sandpaper, but if the plastic has melted, only a complete replacement of the relay will help.
☑️ Relay diagnostics
Necessary tools and preparation
You don’t need a complex professional tool to carry out the work. A standard DIY kit is sufficient. The main thing is to ensure good lighting of the working area, since the compressor area is often dark and cramped.
You will need:
- 🔧 Screwdriver (Phillips and flat) for removing panels and terminals.
- 🔌 Pliers or pliers for working with wires.
- 📏 Multimeter (tester) to check the continuity of the circuit.
- 🧹 Sandpaper or needle file for cleaning contacts.
- 📸 Smartphone for photographing the connection diagram before disassembling.
Before starting work, be sure to wait for complete cooling compressor if the refrigerator has just been running. We don't need heatstroke or burns from hot tubes. It is also recommended to prepare a container for oil drainage if you need to remove the compressor, although when replacing a relay this is rarely necessary.
It is important to choose an exact analogue of the old relay. They differ in engine power, orientation (vertical/horizontal) and type of mounting. The part number is usually stamped on the case or indicated in the technical documentation of the refrigerator.
Step-by-step relay connection diagram
The process of installing a new element requires care. Despite its apparent simplicity, it is very easy to confuse the contacts, especially if the markings are erased. Below is a table of contact correspondence for the most common types of relays.
| Relay type | Contact 1 | Contact 2 | Contact 3 |
|---|---|---|---|
| Starting (vertical) | Phase (L) | Start winding | Grounding/Case |
| Starting protection (RTK) | Network input | Working winding | Start winding |
| Electronic | Input | Run | Start |
| Two-contact | General | Start | - |
First remove the old relay by carefully disconnecting the wires. Do not yank them sharply to avoid damaging the insulation or terminals on the compressor itself. If the wires are stuck, use WD-40 or gently heat the connection (with caution).
Install a new relay on the compressor fitting. It should be put on tightly, with a characteristic click or force. Make sure the orientation matches the markings (the UP arrow or TOP lettering should face up). Then connect the wires according to the photographs taken earlier or color markings.
Checking functionality after installation
After all contacts connected, do not rush to close the back cover. It is necessary to conduct an initial test run. Plug in the refrigerator and listen carefully.
Normal startup is accompanied by a smooth hum of the compressor, which after 3-5 seconds goes into operating mode. If you hear a click, a hum, and then a click again after a couple of seconds, the engine will not start. This could mean an incorrect connection, a malfunction of the new relay itself, or, worse, a compressor wedge.
Check the heating of the relay housing. During operation, it may become slightly warm, but if it becomes too hot to touch, it means that current is constantly passing through it, which is a sign of a malfunction. Also check the presence of voltage at the output to the compressor.
Typical errors when installing yourself
The most common mistake is ignoring the relay orientation. Many models only work in a certain position (usually with the coil facing up). If you install it upside down, gravity will not allow the core to move correctly, and startup will not occur.
The second error is poor contact