A sudden stop of the compressor or a characteristic click, after which the refrigerator Bosch stops cooling, often indicates a failure of the trigger mechanism. This is a common problem that equipment owners encounter, and in many cases it can be solved on their own without calling a technician. Start relay This is a small but critical element that supplies current to the motor windings, starting it up.
Before proceeding with dismantling, it is necessary to completely de-energize the unit. Failure to follow this rule may result in serious electrical injury as the line voltage is 220 volts. Unplug the plug from the socket and move the refrigerator away from the wall, providing free access to the back wall.
The process of removing the part requires a minimal set of tools, but accuracy is key here. Plastic latches and contacts can be fragile, especially if the equipment has been in use for a long time. In this article we will look in detail at how to correctly remove the relaycarry out visual diagnostics and understand whether the unit needs to be replaced.
⚠️ Attention: Before starting any work, make sure that the capacitors in the circuit are discharged, although in modern Bosch models the risk of residual charge is minimal, it is better to be safe and not touch live parts immediately after shutdown.
Design features and location of the relay
In refrigerators Bosch, as in most modern models, the starting relay is located directly on the compressor housing in the lower rear part of the unit. It is a plastic box that fits over three contact pins coming out of the engine. The design may differ depending on the type of compressor: inverter or linear.
The main task of this unit is to briefly supply voltage to the starting winding of the engine at the moment of start. As soon as the motor reaches the required speed, the relay opens the starting winding circuit. If this mechanism sticks or burns out, the compressor either does not start at all, or hums but does not rotate, which often leads to the thermal relay tripping.
To access the part, you do not need to disassemble the entire refrigerator. It is enough to remove the protective cover at the bottom of the rear wall, if it is provided by the design of your model. In some cases, the relay is covered with a metal casing, which also needs to be removed. Location always tied to the compressor, so it is almost impossible to make a mistake.
It is worth noting that in inverter models the starting system can be integrated into the electronic control unit, and a separate mechanical relay on the compressor may not be. In such cases, diagnostics require a different approach and checking the electronics.
How to distinguish an inverter compressor?
Inverter compressors usually have a closed metal casing with no visible mechanical relays on the case, and also operate quieter and smoother than conventional ones.
Necessary tools and worker training places
To successfully complete the task of dismantling the relay, you do not need a complex professional tool. However, having the right tools will speed up the process and protect you from damaging the plastic elements. Preparation of the workplace is also important, since the work will take place near the floor, possibly in poor lighting conditions.
Ensure good lighting of the work area. Use a flashlight or hand-held lamp to clearly see pin markings and wire condition. Dust and dirt on the back wall can hide important parts, so preliminary cleaning will not hurt.
- 🔧 Pliers or pliers - to carefully remove the retaining clips if they are rusty or tight.
- 🪛 Screwdriver (cross or flat) - may be needed for removal protective casing or terminal block.
- 📸 Smartphone with camera —for photographing the wiring diagram before disconnecting them.
- 🧤 Work gloves —to protect your hands from sharp metal edges and possible dirt.
It is important to prepare a container for small parts, such as screws or spring clips, so that they do not get lost in the carpet pile or floor crevices. It is also worth having a multimeter on hand if you plan to immediately check the serviceability of the removed element.
☑️ Preparation for repair
Step-by-step process of dismantling the start relay
Process of removing the relay in refrigerators Bosch standardized, but requires care. The main rule is not to use excessive force. If the part does not come off, then you have missed a retaining element or clamp. Sudden movements can break the plastic mounting ears or damage the compressor contacts.
First remove the back panel of the refrigerator by unscrewing the mounting screws around the perimeter. You will see a view of the compressor and the capacitor wound around it. Locate the black or gray plastic block that fits onto the side of the compressor. This is precisely the starting relay.
Carefully disconnect the wires going to the relay. In some models they are fixed with plastic clips, in others they are simply inserted into the connectors. Remember or take a photo of the color coding of the wires before disconnecting, since mixed up contacts can lead to a short short circuit. After disconnecting the wires, take the relay by the body and pull it down or to the side, depending on the model.
If the relay is mounted on a metal frame, first remove the frame by bending the fixing tabs. The relay can then be easily removed from the compressor pins. Be careful: inside the plastic case there may be a ceramic or metal element that can break if dropped.
⚠️ Attention: It is strictly forbidden to pull the relay by the wires! This will lead to their breakage at the very base, which will require complex soldering and restoration of insulation.
After removal, inspect the inside of the relay. If you see traces of burning, melted plastic, or smell burnt insulation, then the part definitely requires replacement. Also check the condition of the contacts on the compressor itself - they should be clean and not oxidized.
Diagnostics and fault table
After you succeeded remove the relay, it is necessary to understand whether it really caused the breakdown. A visual inspection provides only 50% of the information. More accurate diagnostics can be carried out using a multimeter by checking the resistance of the windings and the integrity of the contacts. However, even without the device, preliminary conclusions can be drawn.
Shake the relay near your ear. If you hear a rattling sound inside, like a loose nut, this is a sure sign of destruction of the internal mechanism or core. A working relay should not make sounds when shaking. Also pay attention to the condition of the contacts: blackening indicates burning.
Below is a table that helps classify symptoms and probable causes of the malfunction:
| Symptom | Probable cause | Action |
|---|---|---|
| The refrigerator hums, but does not start | The compressor piston is jammed or the relay is burned out | Check the relay, try to start the compressor directly (carefully) |
| A click is heard, then silence | The starting relay or thermal relay is faulty | Replace the starting relay |
| The compressor is hot, does not work | Thermal protection has tripped | Allow to cool, check the relay and motor windings |
| A crackling sound is heard inside the relay | The internal mechanism is destroyed | Only replacing the unit |
If visual diagnostics and multimeter testing indicate a malfunction, repairing the old relay is usually impractical. The cost of a new part is low, and the reliability of the restored unit will be questionable. It is better to purchase an original analogue or a high-quality substitute.
Installing a new relay and checking operation
Installing a new starting relay is done in the reverse order of dismantling. It is important to ensure that you purchase a compatible model. There is always a number on the body of the part, which must match the markings on the old element or correspond to the model of your refrigerator Bosch.
Place the new relay on the contact pins of the compressor. It should fit tightly and with slight effort. Make sure the orientation of the part is correct: there is usually an "UP" mark on the body or an arrow pointing up. Incorrect installation may result in the mechanism not working or shorting the contacts.
Connect the wires to the relay terminals according to the photographs taken earlier or color markings. If you used a multimeter, double-check the connections. Install the retaining frame or clips that hold the relay in place. Make sure nothing is loose.
After assembly, plug in the refrigerator. In the first seconds, you can hear the characteristic click and hum of the compressor starting up. This is a normal reaction. If the motor starts running smoothly and after some time cooling appears in the chamber, then the repair was successful.
During the first hours of operation, periodically check the temperature of the compressor housing. It shouldn't get hot. Also listen to the sounds: extraneous knocking or vibration may indicate installation problems or other system malfunctions.
Common mistakes when replacing and safety measures
When repairing refrigerators on their own Bosch beginners often make typical mistakes that can negate all efforts or lead to new damage. One of the most common is ignoring electrical safety rules or careless handling of wires.
Never leave wires dangling without insulation. Even after unplugging from the outlet, voltage may remain in the circuit, and accidentally touching the bare ends when turned on will cause sparking. Use insulating tape or heat shrink to protect connections.
Another mistake is installing the wrong type of relay. They may look the same externally, but differ in internal resistance or type of contacts. Using the wrong part can lead to overloading the compressor windings and causing it to burn out, which is a much more expensive problem.
⚠️ Attention: If, after replacing the relay, the compressor does not start again or the circuit breaker in the panel is knocked out, immediately turn off the refrigerator. The problem may be in the compressor itself (turn-to-turn short circuit) or in the wiring, and further switching on is dangerous.
It is also important not to forget about grounding. If your refrigerator is plugged into an ungrounded outlet, static or even higher voltage may be generated across the cabinet. Make sure that the electrical network in the house is working properly.
If you are not confident in your abilities or the diagnostics show complex faults, it is better to turn to professionals. Repairing a refrigerator is a balance between savings and the risk of losing an expensive unit.
Questions and answers about replacing the relay
Is it possible to repair an old relay if it is burned out?
Theoretically, you can try to disassemble and clean some types of relays (especially old induction ones) contacts. However, modern refrigerators Bosch use sealed plastic cases. Opening them violates the integrity, and reliability after such repairs will be extremely low. Experts recommend only a complete replacement.
Where can I find the relay number to order a spare part?
The part number (art.) is always printed on the body of the relay itself. To see it, it is not necessary to completely remove the part; often it is enough to remove the protective cover of the compressor and photograph the marking. The number can also be found in the technical documentation of the refrigerator or on the manufacturer’s website according to the model of the unit.
Why does a new relay burn out after a short time?
If replacing the relay does not solve the problem and the new part quickly fails, the reason lies deeper. Most often, this is a malfunction of the compressor itself (jamming, short circuit of the windings) or problems with the heat removal system. In this case, the compressor consumes increased current, which melts the relay contacts.
How much does it cost to replace the relay at a service center?
The cost consists of the price of the spare part and the work of the technician. The part itself is inexpensive, but a specialist visit and diagnostics can cost significantly more, especially if the refrigerator is heavy or difficult to access. Self-replacement allows you to save on work.
Is it possible to start a refrigerator without a relay?
There is a method of directly starting the compressor, bypassing the relay for diagnostics, but it is impossible to operate the refrigerator constantly without this unit. The compressor will not be able to work normally, will overheat and quickly fail. The relay is an essential element of the system.