Failure of the starting capacitor is one of the most common reasons why a modern refrigerator stops freezing, although the light inside is on. The owner of household appliances usually hears a characteristic click of the relay, after which the motor hums for a few seconds and then goes silent again. At this moment starting winding receives a powerful impulse, but without the capacitor the engine cannot gain the required speed.
Independent replacement of this element is quite possible if you follow precautions and have a basic set of tools. It is important to understand that the capacitor accumulates an electrical charge, and careless handling of it can lead to an unpleasant electric shock even after disconnecting the device from the network. The purpose of this article - to provide a clear understanding of the physical processes and algorithm of actions for safely restoring the compressor to operation.
Before disassembling the unit, you need to make sure in the diagnosis. Often the symptoms are similar to a breakdown of the starting relay or an interturn short circuit in the windings. If you have determined for sure that the problem lies in the capacity, then further actions will help you bring the refrigerator back to life. Carefully study marking on the old element before buying a new one.
The principle of operation and the role of the capacitor in the system
Single-phase asynchronous motors that are installed in household refrigerators are not capable of creating a rotating magnetic field on their own. To start, they require a phase shift, which is precisely what starting capacitorprovides. It briefly connects the starting winding, creating the necessary torque for the rotor shaft.
As soon as the engine reaches about 75% of the rated rotation speed, the centrifugal switch or starting relay opens the starting winding circuit. From this moment on, the refrigerator operates only on the main (working) winding. If the capacitor has lost its capacity or is broken, the phase shift does not occur, and the motor simply hums, trying to start.
There is also the concept of a working capacitor, which remains in the circuit constantly, but in classic household refrigerators it is the starting circuit that is most often used. Critical important Do not confuse the types of capacitors when replacing, since they have different characteristics and operating modes. An error in choosing the type can lead to overheating and rapid failure of the new part.
⚠️ Attention: Before any work inside the electrical circuit, be sure to disconnect the refrigerator from the power supply. The residual voltage on the capacitor can persist for a long time, so before touching the contacts it is recommended to discharge it through a resistor or dielectric screwdriver.
Diagnostics and signs of malfunction
You can determine the malfunction of the capacitor by indirect signs even before opening the compressor compartment. If the refrigerator hums but does not start, and after a while the thermal relay clicks, this is a sure sign of a problem with the starting circuit. A visual inspection often reveals swelling of the housing or traces of electrolyte.
For accurate diagnosis, you will need a multimeter. In the resistance measurement mode, a working capacitor should show an increase in resistance (charging), and then, when changing probes, a discharge. If the device shows zero or infinity immediately, the part must be replaced. Capacity You can also check with a special tester, if you have one in your arsenal.
Sometimes the cause of failure is not the part itself, but oxidized contacts in the block or a broken wire. Therefore, before purchasing a new element, it is worth checking the integrity of the connecting wires. A common mistake is replacing a working capacitor when the problem lies in a stuck start relay.
Preparation for replacement and selection of components
To carry out the work, you will need a minimum set of tools: pliers, side cutters, a screwdriver and, preferably, a multimeter. You will also need to purchase a new capacitor. The main parameters for selection are capacitance (measured in microfarads, uF) and operating voltage (V).
The capacitance of the new element must match the original as closely as possible. A slight deviation of 5-10% is allowed, but it is better to find an exact analogue. The operating voltage should not be lower, but preferably higher, than that of the standard element. For example, if there was a 250V capacitor, you can safely install it at 330V or 450V.
Pay attention to the overall dimensions of the new part. It must physically fit in a plastic casing or on the terminal box of the compressor. Polypropylene Capacitors are considered more reliable and compact compared to electrolytic counterparts.
☑️ Preparation for replacing the capacitor
Connection diagram and correspondence table
The connection process depends on the type of compressor and the location of the terminals. Usually there are three terminals on the terminal box: two for the working winding and one for the starting winding. The capacitor is always connected in series with the starting winding. The circuit may look different depending on the design of the starting relay.
In some models, the capacitor is attached directly to the relay body, in others it is placed separately. When connecting, it is important to observe polarity if the capacitor is electrolytic (marked + and -). For non-polar starting capacitors, the order in which the terminals are connected does not matter.
Below is a table that helps determine the correspondence of the terminals on common types of compressors. This will simplify the task when testing the windings.
| Compressor type | Designation of the working winding | Designation of the starting winding | Common wire |
|---|---|---|---|
| Atlant / Minsk | R (Run) | S (Start) | C (Common) |
| Don / Biryusa | P (Start) | R (Working) | O (General) |
| LG / Samsung | M (Main) | A (Aux) | C (Common) |
| Indesit / Ariston | 1 (Working) | 2 (Startup) | 3 (General) |
When installing, use only copper wires with a cross-section of at least 0.75 mm². Twists are unacceptable, all connections must be made through terminal blocks or reliable soldering with heat shrink insulation. Contact quality directly affects the heating of the unit and the durability of the repair.
Step-by-step installation instructions
After you have reached the motor-compressor and removed the protective casing, you need to photograph the current position of the wires. This will help you avoid getting confused when assembling. Carefully remove the old capacitor by disconnecting the wires or biting them off if the length allows you to make a new connection.
Secure the new element in the same position using a standard bracket or clamp. Vibration from a running compressor should not damage the contacts. Connect the wires according to the photo or diagram you took earlier. Make sure that the wires do not touch hot parts of the compressor or sharp metal edges.
After assembling the entire electrical circuit, but before installing the casing, you can carry out a test run. Plug in the refrigerator and listen. The engine should start confidently, without a long hum. If the startup was successful, let the unit operate for 10-15 minutes, monitoring the temperature of the condenser housing.
Frequent errors and safety measures
One of the common mistakes is ignoring the state of the start relay. If the relay is faulty, the new capacitor will burn out after a few switching cycles. Always check the mechanical mobility of the relay contacts and the absence of carbon deposits on them.
Also, technicians often forget about discharging the capacitor before checking. Even when unplugged, it retains its charge. Short-circuiting the terminals with a screwdriver may cause a spark and burns. It is safer to discharge it through an incandescent lamp or a powerful resistor.
⚠️ Attention: Do not use capacitors designed for operation in alternating current (AC) circuits in DC circuits, and vice versa. Only specialized starting capacitors marked AC and the appropriate voltage are suitable for refrigerators.
It is important to monitor the compressor temperature after replacement. If the engine heats up more than usual, the container may be selected incorrectly or the piston group may be mechanically jammed. In this case, operation should be stopped.
Checking operation after repair
After successful startup, you need to make sure that the refrigerator has begun to gain cold. During the first hour of operation, the compressor can work continuously - this is normal for reaching the operating mode. Check the uniform cooling of the evaporator.
Pay attention to the absence of extraneous vibrations and humming. The new capacitor should not make any sounds. If you hear a crackling or whistling noise, check the tightness of the wires and the integrity of the insulation.
During the first day of operation, it is recommended to periodically check the temperature of the capacitor body by hand (carefully!). It may get hot, but should not be scalding hot. Excessive heating indicates problems with leakage currents or incorrect capacitance.
Is it possible to start a refrigerator without a capacitor?
Theoretically, you can start the engine by spinning it by hand, but it will not work efficiently and will quickly burn out. Without a capacitor, the torque required to start under a freon load is not created. Operation without a starting element is strictly prohibited.
Why does a new capacitor burn out?
The reasons may be power surges in the network, a malfunction of the starting relay (sticking contacts) or the use of a part with insufficient operating voltage. It is also possible that the part itself is defective or mechanical damage during installation.
What capacity to choose if the original is not found?
The capacity deviation is allowed within ±10% of the nominal value. If you install a much larger capacitance, the inrush current will increase and the winding will overheat. If it is less, the engine may not start or will hum.
Do you need to change the capacitor when replacing the compressor?
Yes, when replacing the compressor, always install a new starting kit (relay and capacitor). Old elements could degrade, and their use with a new motor can lead to the breakdown of an expensive unit under warranty.