Sudden stoppage of the compressor or constant Clicking noises coming from the back of the refrigerator often indicate that the start relay has failed. This small but critical element is responsible for starting the engine by supplying the necessary impulse to the windings. If you notice that the engine hums but does not start, or it turns on for just a couple of seconds and immediately stalls, there is a high probability that the relay needs to be replaced.
Doing this procedure yourself allows you to save a significant amount on calling a technician, since the process itself does not require complex professional equipment. However, it is important to understand that working with electrical components requires strict safety precautions and attention to detail. Before proceeding with disassembly, it is necessary to completely de-energize the unit by unplugging the power cord from the outlet.
In this article we will analyze in detail the trigger mechanism, methods for diagnosing the malfunction and the algorithm for replacing the part. You will learn how to choose the right analogue for your model Indesit, Atlant or Bosch, and what tools you will need for high-quality repairs. A competent replacement will bring the equipment back to life and ensure stable operation of the cooling system.
Symptoms of a faulty start relay
You can determine what exactly starting relay has failed by the characteristic sounds and behavior of the compressor. Most often, a breakdown manifests itself in the form of a series of loud clicks with an interval of 10-20 seconds. At this moment, the engine tries to start, hums, but then the shutdown click is heard, and there is silence. This means that the thermal protection is triggered due to the inability of the rotor to turn.
Another obvious symptom is overheating of the rear wall of the refrigerator in the lower part, where the motor-compressor is located. If the relay is stuck closed, current continues to flow to the starting winding, causing severe heating and subsequent burning of the insulation. In some cases, you can smell a burning smell or see soot on the part itself.
- 🔊 The compressor makes a loud click and stops immediately.
- 🔥 The motor-compressor gets very hot, but no cold is produced.
- 💡 The light in the refrigerator compartment is on, but the engine does not start.
- ⚡ Triggering of circuit breakers in the electrical panel when the refrigerator is turned on.
Sometimes the cause of failure is not only mechanical damage to the contacts, but also oxidation of the terminals. If you have not carried out preventive maintenance for a long time, a coating may have formed on the contacts, preventing the normal passage of current. A visual inspection often helps to identify blackened areas or melted housing plastic.
⚠️ Attention: If the situation has not changed after replacing the relay, the problem may lie in an interturn short circuit of the compressor itself or a break in the windings. In this case, further operation may lead to the final failure of the unit.
Design and principle of operation of the relay
The starting relay is an electromechanical switch that automatically connects the starting winding of the engine at the time of start. Inside the housing there is an inductor, a movable core and a contact group. The principle of operation is based on a current jump at startup: the magnetic field of the coil draws in the core, closing the contacts of the starting winding.
As soon as the rotor gains the required speed, the current in the circuit drops, the magnetic field weakens, and under the influence (of gravity) or a spring, the core returns to its original position, opening the circuit. Modern models often use posistor relays, where the role of a switch is played by a thermistor that changes its resistance when heated.
It is important to distinguish between the types of devices, since they are not always interchangeable. Induction relays are sensitive to orientation in space: on their body there is usually an arrow indicating the “up” direction. Installing such a relay upside down will prevent the core from falling and opening the contacts, which will cause overheating.
How do posistor relays differ from induction relays?
Posistor relays do not have moving mechanical parts. Inside them there is a ceramic element (posistor), which, when current is supplied, heats up and sharply increases the resistance, opening the circuit. They are less sensitive to position, but are afraid of moisture and mechanical shock.
The device body is usually made of plastic and is marked with technical characteristics. It is these data, such as operating current and compressor type, that are key when selecting a new part. An incorrectly selected relay may not start the engine or burn out in the first minutes of operation.
Necessary tools and preparation
For successful repairs, you will need a minimum set of tools that can be found in the arsenal of any home craftsman. The main requirement is safety and the ability to carefully remove protective covers without damaging the wires. Before starting work, make sure that the refrigerator is unplugged for at least 30 minutes.
You will need pliers with insulated handles to grip wires and terminals. Needle-nosed pliers or wire cutters will be useful if you need to strip contacts or cut off old wire. Also, a screwdriver (Phillips or flat, depending on the fastening of your unit) will not be superfluous.
- 🛠️ A set of screwdrivers (flat and Phillips).
- 🔧 Pliers and wire cutters.
- 🧤 Dielectric gloves (recommended).
- 📸 Smartphone for photographing the connection diagram.
Pay special attention to organizing the workplace. The back wall of the refrigerator should be well lit, and the space around it should be free of foreign objects. If you are changing the relay in a refrigerator Liebherr or other built-in appliances, you may need to move the unit away from the wall.
☑️ Preparing to replace the relay
Prepare a container for small parts in advance so as not to lose screws or terminals. If the relay is clip-on, make sure you have a thin screwdriver or knife to gently press it out without breaking the plastic.
Step-by-step instructions for replacing the relay
The first step is to remove the protective casing from the compressor. It is usually secured with a few screws or latches. Be careful not to damage any refrigeration pipes that may be located nearby. After removing the cover, you will see a black cylindrical or box-shaped compressor.
On the side or top of the compressor (depending on the model) there is the same relay mounted on the compressor rod. It can be closed with an additional plastic cover or a metal bracket. If there is a bracket, it must be carefully removed with pliers. Then disconnect the wires that go to the relay.
Remove the old relay from the compressor rod. It may be a tight fit, so rock it slightly from side to side. Be prepared for the fact that there may be condensation or traces of oil inside - use a rag. Install the new relay, observing the correct orientation (the "UP" or "Up" arrow should face up).
Connect the wires to the terminals of the new device according to the photographs taken earlier. Make sure the contacts are tight and not loose. Replace the relay protective cover (if there is one) and secure the compressor housing in place. Only after complete assembly can you turn on the refrigerator into the network.
| Work stage | Action | Important detail |
|---|---|---|
| Dismantling | Removing the casing and old part | Not pull the wires, only the relay body |
| Check | Visual inspection of the contacts | Make sure there is no carbon deposits on the terminals |
| Installation | Installation of a new one relay | Observe the "Top" marking on the case |
| Test | Plugging into the network | The first start may take up to 5 minutes |
After turning on, listen to the operation of the motor. It should start with a characteristic hum and run smoothly, without any extraneous clicks. If after 10-15 minutes the back wall begins to cool and cold appears in the chamber, it means relay replacement it was successful.
Selecting the right spare part
Selecting the right relay is the key to longevity of the repair. There are practically no universal solutions here, since the starting currents differ for different compressors. The main selection parameter is the engine power, which is usually indicated on the nameplate of the compressor itself (for example, 1/5 HP, 1/4 HP).
It is also important to consider the type of compressor: regular or inverter. For inverter systems, such as Linear Compressor ot LG, conventional relays are not suitable, since control there is carried out by an electronic board. An attempt to install a mechanical relay on an inverter motor will lead to damage to the electronics.
- 🏷️ Pay attention to the manufacturer's markings (Danfoss, Secop, Embraco).
- 🔢 The part code is often stamped on the old relay body itself.
- ⚡ The operating current must correspond to or be slightly higher than the motor rating.
- 📐 The overall dimensions must allow installation in a standard location.
If you cannot find an original spare part, there are universal kits that are suitable for a wide range of compressors. They are often supplied with a set of adapters and terminals, which simplifies installation. However, it is better to look for an analogue that is as close as possible in characteristics to the original.
When purchasing, be sure to check the integrity of the case and the absence of traces of oxidation on the contacts. Even a new part can be defective if it has been lying for a long time in unsuitable storage conditions, for example, in a damp warehouse.
Frequent errors and precautions
One of the most common mistakes is ignoring the orientation of the relay during installation. As mentioned earlier, many devices only work correctly in a vertical position. If you install the relay horizontally or upside down, the contact opening mechanism will not work, which will lead to burnout of the starting winding.
Another error is poor contact in the terminals. If you don't insert the wires all the way or they are oxidized, sparking and heating will occur at the connection. This may cause a fire or the relay may fail again after a few days of operation. Always clean the contacts to a shine before installation.
⚠️ Attention: It is strictly forbidden to close the relay contacts directly (“directly”) to test the compressor without special equipment. This can lead to instantaneous burnout of the windings or electric shock.
Also, do not ignore the condition of the compressor itself. If, after replacing the relay, the motor continues to hum and knock out plugs, it may be jammed. In this case, no replacement of the relay will help; more complex repairs or replacement of the entire compressor will be required.
Do not forget that the technical characteristics and design of refrigerators may vary depending on the year of manufacture and the specific modification. Always check the technical documentation or the markings on the nameplate of your device before starting work.
FAQ: Frequently asked questions
Is it possible to repair an old relay if it is burnt out?
In most cases, repairing an old relay is impractical. The internal contacts burn out, and the posistor changes its properties. Trying to clean the contacts will give a temporary effect for several hours or days. The cost of a new part is low, so it is safer to make a complete replacement.
Why did the new relay burn out after a week?
This may indicate a malfunction of the compressor itself (turn-to-turn short circuit), problems with the wiring, or incorrect selection of the relay for current. Also, the cause may be a power surge in the network or poor contact in the terminal block, causing local overheating.
Is a relay from another brand of refrigerator suitable?
Yes, if the main parameters match: compressor power, type of connection and overall dimensions. The brand of the refrigerator (for example, Samsung or Whirlpool) is secondary, the main thing is the characteristics of the motor-compressor itself on which the relay is installed.
How long does it take to replace the relay?
For an experienced technician, the process takes 15-20 minutes. When replacing it yourself, taking into account the search for tools, photography and careful assembly, you should allow about 40-60 minutes. The main thing is to take your time and do everything step by step.