A sudden failure of a refrigerator often takes you by surprise, and one of the common causes of failure is the failure of the electrical part of the motor. If, when connected to the network, the unit hums but does not start, or after a few seconds a click is heard and silence sets in, the problem may lie in the starting element of the circuit. It is starting capacitor that provides the necessary torque to rotate the engine shaft at the time of start.
Many old-school craftsmen prefer to start the compressor without this element, using a button or direct connection, however, modern refrigerator models such as Atlant, Beko or Indesit, designed to work in conjunction with a capacitor. Ignoring this unit leads to overheating of the windings and rapid combustion of the expensive compressor. In this article, we will look at how to choose the right replacement so as not to harm the equipment.
Understanding the operating principle of this component will help you avoid unnecessary expenses on calling a technician for simple diagnostics. Condenser accumulates an electrical charge and releases it at the right moment, creating a phase shift in the starting winding. Without this process, the motor rotor simply will not be able to overcome inertia and begin to rotate under refrigerant pressure.
The principle of operation of the compressor starting circuit
In order to figure out exactly what element your refrigerator needs, you need to understand the basic operating diagram of a single-phase asynchronous motor. Unlike industrial three-phase motors, household compressors operate from a regular 220 volt outlet. One phase is not enough to create a rotating magnetic field, so the motor design has two windings: the main (working) and additional (starting) windings.
The main winding is wound with a thicker wire and is designed for constant operation. The starting winding is turned on only for a short time at the start. It is in the circuit of this winding that it is connected in series. starting capacitor. Its task is to create a phase shift in the current, which generates torque. As soon as the shaft picks up speed, the starting circuit should turn off.
In old models of refrigerators, for example, in Soviet ones ZIL or Saratov, a starting relay with a thermocouple was responsible for disconnecting the starting winding. Modern systems often use a circuit where a capacitor operates in conjunction with a start relay, or compressors with a permanent capacitor on (CSR circuit) are used. It is important not to confuse the types of circuits, since an incorrect connection will result in the motor humming but not spinning.
If you open the compressor casing, you will see that the wires from the relay and capacitor are suitable for the contacts. Electric capacitance measured in microfarads (μF) and is a critical parameter. A capacitance that is too small will not provide a sufficient impulse to start, and a capacitance that is too large will cause overheating of the windings and insulation breakdown.
Types of capacitors: starting and running
When looking for a replacement, it is important not to make a mistake in the type of device. There are two main types of capacitors most often found in household appliances, which perform different functions, although they may look similar in appearance. The first type is starting capacitors (Starting Capacitor). They are included in the circuit only while the engine is starting (usually for 1-3 seconds) and the relay is immediately turned off. Their main characteristic is high capacity at a relatively low operating voltage.
The second type is working capacitors (Running Capacitor). They remain connected to the circuit constantly while the compressor is running. Such elements are often used in refrigerators with inverter compressors or dual compressor systems to improve energy efficiency. They have a lower capacity, but are designed for long-term operation under voltage.
There are also universal models that can operate in both modes, but their use requires precise calculation of the parameters. For most household refrigerators with piston compressors (brands Danfoss, Secop, Aspera), starting electrolytic capacitors in a black plastic case are used.
When visually inspecting a faulty element, you can often notice swelling of the case, traces of gel-like electrolyte or melting of the contacts. If the capacitor looks intact, but the refrigerator does not start, a check with the device is necessary. Multimeter in the capacitance measurement mode it will show the real value, which should coincide with the markings on the case with a tolerance of ±5-10%.
Key parameters: capacitance and voltage
The most important question when selecting a spare part: what numbers to look for on the body? The main parameter is the capacitance, which is indicated in microfarads (µF or mF). For household refrigerators, this parameter usually varies in the range from 30 to 150 μF. The exact value depends on the compressor power and the type of refrigerant.
The second critical parameter is the rated voltage. The standard value for household appliances is 220V, 230V, 250V or 300V Never install a capacitor with a voltage below 220 Volts, since at the moment of start-up voltage surges occur that will instantly break through weak insulation. You can use an element with a higher voltage (for example, 330V or 400V instead of 250V), but not vice versa.
Current frequency also matters, although in CIS networks it is standard - 50 Hz. Some imported capacitors may be rated at 60 Hz, which is acceptable but may slightly change the startup characteristics. Also pay attention to the temperature range. It can be hot inside the compressor casing, so the element must withstand heating up to +70...+85°C.
To select an analogue, the rule is often used: for every 100 W of engine power, approximately 7-10 μF of capacitance is required. However, it is most accurate to focus on the markings of the old element or the correspondence table for a specific compressor model. An error in the choice of capacitance by more than 20% can lead to unstable operation.
⚠️ Attention: Before any work on replacing the capacitor, be sure to disconnect the refrigerator from the power supply! Even after switching off, the capacitor may retain a residual charge. Close its contacts with a screwdriver with an insulated handle before touching with your hands to avoid electric shock.
Selection table for capacitors for popular compressors
To simplify the search task, we have compiled a summary table of correspondence for the most common models of compressors installed in refrigerators Atlant, Stinol, Indesit and others. Please note that manufacturers may change the equipment, so checking with the markings on your device is required.
| Compressor model | Refrigerant type | Recommended capacitance (μF) | Rated voltage (V) | Connection type |
|---|---|---|---|---|
| Secop (Danfoss) NL | R134a | 61 - 88 μF | 220-250 V | Start relay + Capacitor |
| Aspera (Tecumseh) T | R600a | 30 - 45 uF | 220-250 V | Start relay + Capacitor |
| Embraco (Aspera) NT | R134a | 50 - 70 μF | 220-250 V | Start relay + Capacitor |
| GMCC (Toshiba) R series | R600a | 35 - 50 μF | 250-300 V | Built-in starting |
| Atlant SKN compressors | R134a | 70 - 90 µF | 220 V | Start relay + Capacitor |
The table shows that for refrigerant R600a (isobutane), which is explosive, compressors of lower power are often used, requiring capacitors of smaller capacity. For more powerful models, elements with greater capacitance are required. If you do not find an exact match, you can use a capacitor with a capacity that differs by +/- 10% from the nominal value. R134a elements with greater capacitance are required. If you do not find an exact match, you can use a capacitor with a capacitance that differs by +/- 10% from the nominal value.
Instructions for replacing the capacitor with your own hands
Replacing the capacitor is one of the few procedures in refrigerator repair that you can do yourself, without deep knowledge of electronics and special tools. The main thing is to follow the sequence of actions and safety precautions. The process will take no more than 15-20 minutes.
First, provide access to the compressor. To do this, move the refrigerator away from the wall and remove the rear metal panel (casing) covering the engine compartment. In some models, for example Liebherr or Bosch, you may also need to remove the plastic cover above the compressor. Make sure the power cord is unplugged.
Locate the capacitor. This is usually a black plastic cylinder or parallelepiped mounted on the frame or on the compressor itself. There are two wires going to it. Take a photo of the connection diagram so as not to mix up the wires during assembly. Carefully disconnect the terminals or cut the wires (leaving some room for twisting), then remove the mounting clamp.
Install the new element in the same position, preferably vertically, to avoid overheating. Connect the wires. Unless the new capacitor is marked with polarity (which is rare for AC), the order in which the wires are connected does not matter. After installation, check the reliability of the contacts.
☑️ Checklist before the first start
⚠️ Attention: Do not leave the wires simply twisted. Use insulating tape or heat shrink. Vibration and moisture condensation are possible in the engine compartment, which can lead to a short circuit or corrosion of the contacts.
Diagnostics and common selection errors
Often home craftsmen are faced with a situation where replacing the capacitor does not solve the problem. The refrigerator hums and clicks, but does not start. In this case, the problem may not be in the tank, but in the compressor itself or the start relay. It is important to conduct a comprehensive diagnosis before purchasing spare parts.
One of the common mistakes is installing the capacitor “by eye” or using elements from other equipment, for example, washing machines or air conditioners. The capacitor from the air conditioner may have too large a capacity, which will lead to overheating of the starting winding of the refrigerator. It is also not recommended to use old Soviet capacitors, since the electrolyte in them could have dried out over decades of inactivity.
If after replacing the capacitor the compressor starts, but after 5-10 minutes the thermal relay turns off, the capacitance may be selected incorrectly (too large) or there is a problem with cooling the motor itself. Check whether the capacitor and radiator are clean and not clogged with dust.
Another mistake is ignoring the state of the start relay. Often the capacitor fails precisely because of the “sticking” of the relay contacts, which does not turn off the starting winding in time. Start relay and it is better to change the capacitor in pairs, since their resource is approximately the same.
Is it possible to start a refrigerator without capacitor?
Theoretically, some models of low-power compressors (up to 100 W) can start without a capacitor if you simply apply voltage to the starting winding through a relay. However, this creates a huge load on the shaft and windings. Long-term operation without a capacitor will cause the motor to burn out within days or even hours. Use this method only for a short-term check of the compressor's performance.
Frequently asked questions (FAQ)
Is it possible to install a capacitor with a larger capacity than what was installed?
It is not recommended to exceed the nominal value by more than 10-15%. A larger capacitor will create too much inrush current, which can damage the motor's starting winding or cause the thermal relay to nuisance trip. If the difference is 5-10 uF, this is acceptable, but it is better to find an exact analogue.
Why does a new capacitor burn out after a week?
Most often the reason lies in a faulty starting relay. If the relay “sticks” and does not open the starting winding circuit after starting, the capacitor continues to operate under a load for which it is not intended (it is designed for a short-term pulse). Also, the cause may be low voltage in the network or overheating of the compressor.
Where is the capacitance marking on the capacitor?
The marking is usually printed in white or silver on a black body. Look for a number labeled "µF","mF" or "MFD". For example, "88 µF" or "100 mF". The voltage (V or VAC) and frequency (Hz) are also indicated there.
What is the difference between 220V and 300V capacitors?
The difference in the voltage safety margin. A 300V capacitor will withstand stronger voltage surges in the network without breakdown. It can be safely installed instead of 220V. But installing 220V instead of 300V is risky - if there is a voltage surge, it can explode.
Is it necessary to discharge the capacitor before installation?
There is no need to discharge a new capacitor. An old, dismantled capacitor, on the contrary, must be discharged before disposal or re-inspection by shorting its contacts with a metal object with an insulated handle to avoid electric shock.