Sudden stopping of the compressor or characteristic clicks when trying to start the refrigerator often indicate a failure of the start-up protection device. This small but critical component is responsible for providing a starting pulse to the motor windings, allowing it to reach the required speed. If the relay is faulty, the motor hums but does not start, or it turns on for only a couple of seconds, after which the thermal protection is activated.
Replacing this element yourself can save a significant amount on calling a technician, since the procedure is technically simple and does not require specialized equipment. However, before starting work, it is important to understand the principle of operation of the unit and observe electrical safety measures so as not to damage the expensive compressor or wiring. In this article, we will analyze all the stages of diagnosing and installing a new relay so that your refrigerator works like new again.
The design and principle of operation of the starting relay
Starting relay is an electromechanical switch that closes the circuit of the engine starting winding at the moment of start. Classic models use the electromagnetic principle: current passing through a coil creates a magnetic field that draws in the core and closes the contacts. As soon as the motor rotor picks up speed, the current drops and the spring opens the circuit, leaving only the main winding to work.
It often works in parallel with the starting function thermal relay, protecting the motor from overloads. Inside the case there is a bimetallic plate, which bends when heated from increased current. If the compressor operates in emergency mode or is jammed, the circuit breaks, preventing the windings from burning out. That is why, during repairs, the entire unit assembly is often replaced, even if only one part is visually burned out.
Modern refrigerators can be equipped with positor relays, where the role of a switch is performed by a ceramic element that changes the resistance when heated. Such devices are more reliable, have no moving mechanical parts and are less susceptible to wear and tear from vibration. However, the principle of checking and replacing them remains the same: it is necessary to ensure correct connection of the contacts to the corresponding terminals of the compressor.
⚠️ Attention: There may be a residual charge or mechanical tension of the springs inside the relay housing. Be careful when opening the case to avoid injury or short circuit.
Understanding exactly how your refrigerator starts the motor will help you quickly find the cause of the breakdown. If you hear a loud click and buzz, but there is no startup, the problem most often lies in sticking contacts or breakdown of the coil. A visual inspection of internal components often shows clear signs of overheating, such as blackening of the plastic or melting of the contacts.
Diagnostics of faults before replacement
Before buying a new part, you need to make sure that the problem is in the relay, and not in the compressor or wiring itself. The first sign of a malfunction is a characteristic sound: a series of clicks at intervals of several minutes, accompanied by a short hum. This means that the thermal protection is triggered because the engine cannot start.
For an accurate diagnosis, remove the relay from the compressor and inspect its internals. If soot is visible inside, there is a burning smell, or the contacts look welded, the part definitely needs to be replaced. Also check the integrity of the coil and the mobility of the core - it should move freely inside the guides and return to its original position under the influence of gravity.
The electrical circuit can be checked using a multimeter in continuity mode. The resistance between the contacts responsible for the starting winding must be minimal (closed) in operating condition or open at a certain position. For posistor elements, the resistance in a cold state is usually 20-50 Ohms, and when heated it increases sharply to thousands of Ohms.
If the relay is working properly, but the refrigerator does not work, the problem may be in the compressor itself. Try applying power directly (safely) to see if the motor starts. If there is no start even with a direct connection, there may be an interturn short circuit or a mechanical wedge in the piston group, which requires more serious repairs.
Necessary tools and safety measures
To carry out the work, you will need a minimum set of tools that can be found in every home. The main thing is to ensure safe working conditions, since you will be working with electric current and refrigerant. Incorrect actions may result in electric shock or damage to the cooling system.
- 🔧 Screwdrivers: flat and Phillips for removing the casing and terminal box.
- 🔌 Pliers: for carefully removing terminals and fixing wires.
- 📏 Multimeter: to check circuit continuity and resistance.
- 🧤 Safety gloves: to protect hands from sharp edges and contamination.
Most An important rule is to completely disconnect the device from the power supply. It is not enough to simply turn off the refrigerator with a button; you must unplug the cord from the outlet. It is also recommended to move the unit away from the wall to provide easy access to the rear panel and compressor. Work in a well-lit area to see the wire markings and the condition of the contacts.
Pay attention to the condition of the wiring. If the insulation of the wires going to the relay is melted or cracked, they must be replaced or repaired using heat shrink. The use of damaged wires can lead to a short circuit immediately after turning on the equipment.
Step-by-step instructions for removing the old relay
The dismantling process begins by removing the protective cover at the bottom rear of the refrigerator. It is usually secured with latches or screws. Carefully unscrew the fasteners and remove the plastic or metal cover, opening access to the compressor and attachments.
At the end of the compressor you will see a box with wires, inside of which is the part you are looking for. The relay is attached directly to the terminals of the motor windings. To remove it, you must first disconnect the appropriate wires, and then carefully pull the relay housing down, freeing the contacts.
☑️ Algorithm for removing the relay
When removing, be careful: old parts may stick to the terminals or become brittle over time. Do not use excessive force to avoid breaking the ceramic insulators or tearing off the wires. If the relay sits tightly, you can slightly rock it from side to side, gradually pulling it down.
After dismantling, inspect the contact group on the compressor itself. Oxidized or burnt leads must be cleaned with fine sandpaper to a metallic shine. This will ensure reliable contact with the new relay and prevent heating at the connection point.
Connection diagram and installation of a new relay
Installing a new starting relay requires attention to the markings. There are always markings on the body of the part and on the terminals of the compressor: S (Start) - starting winding, R (Run) - working winding, C (Common) - common wire. An incorrect connection can instantly damage the new part or damage the motor windings.
Insert the new relay onto the compressor terminals until it stops. It should fit tightly and not wobble. Orientation is important: on many models there is an arrow UP or TOPthat should point straight up. This is necessary for the correct operation of the gravitational switching mechanism.
| Marking | Purpose | Wire color (typical) | Location |
|---|---|---|---|
| C | General contact | Red or black | Bottom left |
| S | Start winding | Blue or green | Top |
| R | Working winding | White or yellow | Bottom right |
| ⏚ | Grounding | Yellow-green | On case |
Connect the wires to the corresponding relay terminals. If the terminals on the new relay differ in shape or location from the old ones, use adapters or carefully cut the old terminals, connecting the wires by color or marking. Be sure to insulate the connection points.
What to do if the new relay does not fit in the seat?
Sometimes manufacturers change the design. In this case, you can carefully disassemble both relays (old and new) and rearrange the internal filling into the body of the old one if the electrical parameters match. However, it is better to purchase an exact analogue using the catalog number.
Secure the wires so that they do not touch the hot condenser tubes or moving parts. After installation, check that all connections are firmly secured by lightly rocking. Make sure that there are no foreign objects or tools inside the terminal box.
Checking operation and typical errors
After assembly, turn on the refrigerator. In the first seconds you can hear a characteristic click and the engine starts. If the compressor started working smoothly, without humming or vibration, and after some time cold appeared in the chamber, then the repair was successful.
One of the common mistakes is ignoring the type of refrigerant and the features of the compressor. For inverter models or systems with linear compressors conventional relays are not suitable, since they use electronic speed control. An attempt to install a mechanical relay on such a system will lead to breakdown.
⚠️ Attention: If after replacing the relay the compressor hums again and knocks out the protection after 5-10 seconds, immediately turn off the device. This may indicate a malfunction of the compressor itself or incorrect connection phasing.
Also monitor the temperature of the new relay housing during operation. It may get hot, but should not be hot. Excessive heating indicates poor contact or mismatch between the parameters of the engine power part.
Frequently asked questions (FAQ)
Is it possible to solder the contacts in an old relay instead of buying a new one?
Theoretically, it is possible to clean the contacts, but this is a temporary solution. The factory coating (silver or special alloys) is removed by sanding, and the copper contacts quickly oxidize and are welded again. In addition, the calibration of thermal protection is violated. It is better to replace the entire part.
Why does a new relay burn out a week after installation?
Most often this happens due to problems with the compressor itself (increased current consumption, jamming) or unstable voltage in the network. Also, the reason may be incorrect installation (not in the arrow direction) or the use of a relay with inappropriate power characteristics.
How to choose an analogue if the original relay is not on sale?
Look for the relay by the catalog number indicated on the case. If the number is not readable, select an analogue based on the compressor power (indicated on the refrigerator tag, for example, 1/4 HP, 1/3 HP) and the type of refrigerant. It is important that the connection type and orientation (vertical/horizontal) match.
Is it dangerous to leave the refrigerator running without a relay casing?
Yes, it is dangerous. The casing protects against moisture, dust and insects, which can cause a short circuit. It also prevents accidental contact with live parts. It is not recommended to operate equipment without a protective cover of the terminal box.