Sudden stop of the compressor or a characteristic click, after which the refrigerator stops cooling often indicate problems in the engine starting electrical circuit. One of the most common causes of such a breakdown is failure starting capacitor. This small cylindrical or rectangular element is responsible for creating the initial torque necessary to accelerate the compressor rotor.
If you notice that the motor is humming but does not start, or the refrigerator turns on for just a few seconds and immediately turns off, diagnosing the capacitor should be the first step before calling a technician. It is important to understand that timely checking can save more expensive components of the unit from overload and burnout of the windings.
In this article we will analyze in detail the algorithm of actions for removing and testing the element using various methods. You will learn how to use a multimeter correctly, what visual signs of defects to pay attention to, and whether it is worth repairing this component at all or whether it is easier to replace it.
Symptoms of a faulty starting capacitor
Before disassembling the equipment, it is necessary to accurately identify the problem. A faulty capacitor often behaves in a specific way, and these signs are difficult to confuse with other failures. The compressor may try to start, emitting a loud hum, but the rotor never starts moving.
In some cases, the motor runs jerkily or starts only when the shaft is manually cranked (which requires opening the compressor housing and is not recommended for beginners). Also, an alarming signal is the heating of the capacitor itself - if after trying to start it is hot to the touch, its capacity is broken.
The main external and sound signs indicating the need for checking:
- 🔊 The compressor hums for 3-5 seconds, then the relay clicks and the motor stops.
- 🔥 The capacitor body is swollen, blackened or has traces of electrolyte leaks.
- ❄️ The refrigerator has stopped freezing, although the light inside is on and the thermostat is working.
- ⚡ When starting, the circuit breaker in the apartment's electrical panel knocks out.
⚠️ Attention: If you smell burning or see sparking in the compressor area, immediately unplug the refrigerator. Further use may result in a fire.
Sometimes the symptoms may be vague. For example, the refrigerator works, but consumes significantly more electricity, and the compressor overheats. This indicates that capacitor capacity has fallen, and the motor does not have enough power to operate effectively under load.
Safety measures and preparation for diagnostics
Working with electrical appliances, especially such powerful ones as a refrigerator, requires strict adherence to safety rules. A voltage of 220 volts is dangerous to life, and capacitors can retain a charge for a long time even after being disconnected from the network.
First of all, it is necessary to completely de-energize the unit. Don’t just turn it off with a button, if there is one, but pull the plug out of the socket. Only after this can you begin to dismantle the protective cover at the bottom of the refrigerator, where the compressor is located.
Before touching the contacts of the capacitor, be sure to discharge it. To do this, carefully close its two terminals with a screwdriver with an insulated handle. If a spark flashes, it means the element has been charged, and you have avoided electric shock or damage to the tester probes.
☑️ Preparation for testing
To carry out high-quality diagnostics you will need:
- 🛠️ Multimeter (digital or analog) with the function of measuring resistance and capacitance.
- 🔧 A set of screwdrivers for removing the compressor casing.
- 🧤 Dielectric gloves (recommended for additional protection).
- 📸 Phone camera (to photograph the connection diagram before disassembling).
It is important to work in a dry room. Moisture on the floor or hands may distort instrument readings or create a hazardous situation. If you are checking in winter in an unheated garage, allow the capacitor to warm up to room temperature, since the cold affects the dielectric properties.
Visual inspection and dismantling of the element
After removing the protective casing, you will see the black “barrel” of the compressor, to which a plastic box is attached. It is inside it or next to it that the desired element is located. In modern models, it is often integrated into the start relay; in older models, it can stand separately.
Carefully disconnect the wires. The rule stated above applies here: take a photo. The colors of the wires from different manufacturers (Indesit, Atlant, LG) may differ, and it can be difficult to put everything back together “from memory”. Unscrew the capacitor mount and remove it.
Carefully inspect the body of the part. Any physical deformation is a 100% sign of failure. Swelling of the ends, cracks in the plastic, traces of soot or leaked liquid indicate that the inner lining is broken or the seal is broken.
⚠️ Attention: If traces of oil are visible on the condenser, check the compressor. Sometimes the capacitor fails due to vibration or old age, but sometimes the cause is a freon leak, causing the motor to wear out.
Even if the element visually looks perfect, this does not guarantee its serviceability. An internal break or loss of capacity is not always accompanied by external effects. Therefore, let's move on to an instrumental check.
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Check with a multimeter in ohmmeter mode
The most accessible diagnostic method is to use a multimeter in resistance measurement mode. Switch the device to the sector Ω to the limit of 2000 kOhm (2 MOhm). If you have a dial gauge, select the appropriate range.
Touch the capacitor leads with the probes. The digital multimeter will first show a sharp jump in the numbers, and then the value will begin to gradually increase to infinity (one in the most significant digit). This indicates the charging process and the serviceability of the dielectric.
If a unit (infinity) immediately lights up on the screen, it means that a break has occurred inside. If the device shows zero or very low resistance and does not change, a short circuit of the plates has occurred. In both cases, the part must be replaced.
For clarity, we present a table of readings and their explanation:
| Multimeter reading | Dynamics of changes | Diagnosis |
|---|---|---|
| Starts small, grows to 1 | Smooth increase | Good |
| Unit (∞) immediately | Missing | Break circuit |
| Zero or low number | No change | Short circuit |
| Chaotic jumps | Unstable | Broken contact/breakdown |
It is worth noting that this method does not show the exact capacity, but only confirms the integrity of the structure. For deeper diagnostics, it is better to use the capacitance measurement mode, if your device allows it.
Measuring capacitance and checking voltage
Modern digital multimeters often have a capacitance measurement mode, indicated by a letter F or a capacitor symbol. This is the most accurate method. Switch the toggle switch to the appropriate position and connect the leads.
The capacitor body always indicates its nominal capacitance (for example, 16 µF or 20 µF) and the permissible deviation (usually ±5%). If the device shows a value that differs from the nominal value by more than 20%, such a capacitor will not be able to ensure normal engine starting.
Why does the capacitance drop?
Over time, the electrolyte inside the capacitor dries out, which leads to a decrease in the working area of the plates. This is a natural aging process, which is accelerated by high temperatures and voltage surges in the network.
Checking voltage (voltage) is rarely done in domestic conditions, as it requires a power supply. However, if you decide to check the operation in the circuit, make sure that the voltage at the terminals during operation corresponds to the rating data (usually 250-450 Volts).
Remember that operating voltage the capacitor indicated on the case must be no less than in the circuit. If you put a part at 250V instead of 450V, it will burn out quickly. Reverse replacement (more volts with smaller ones) is allowed and even desirable for reliability.
⚠️ Attention: Do not test the capacitor “for a spark” by connecting it directly to an outlet without load. This is a crude method that can completely destroy the element or damage the wiring, and also does not provide any information about the actual capacity.
Correspondence table and selection of replacement
If diagnostics have confirmed a malfunction, it is necessary to select a new element. It is critical to follow the parameters. The main characteristics are capacitance (uF), operating voltage (V) and type (starting/operating).
Refrigerators mainly use starting capacitors, which operate for a short time. Their parameters may differ from those used in air conditioners or pumps.
Indicative table of correspondence between compressor power and condenser capacity:
| Compressor power | Refrigerant type | Recommended capacity | Voltage |
|---|---|---|---|
| 1/6 - 1/4 hp | R134a / R600a | 10 - 16 μF | 250-300 V |
| 1/3 hp | R134a / R12 | 16 - 20 µF | 300-350 V |
| 1/2 hp | R22 / R404a | 25 - 30 µF | 350-450 V |
| 3/4 hp and higher | Industrial | 40 - 50 µF | 450 V |
When purchasing, pay attention to the temperature range. Low temperatures are important for refrigerators, although the condenser itself is in the warm zone of the compressor. Marking -40...+85°C will be optimal.
Do not try to gain the required capacitance by connecting several capacitors in parallel, unless there is an urgent need for it. Every extra connection is a potential point of failure and increased resistance.
Frequent errors and questions during replacement
Many amateur craftsmen make mistakes that lead to repeated failure. The most common one is ignoring the type of capacitor. Starting and working elements have different designs and purposes.
Starting elements are designed for short-term operation (a few seconds at start). Workers (Running) function constantly. If you put the trigger in the place of the worker (or vice versa, in circuits where this is important), the system will quickly fail.
They also often forget to check the start relay. If a capacitor burns due to a power surge, the relay could become stuck closed, continuing to supply current to the winding and causing overheating. Always check the entire bunch.
In conclusion, replacing a capacitor is a simple procedure, but requires care. If, after replacement, the new element also quickly fails, the problem lies deeper - perhaps in an interturn short circuit of the compressor windings or a wiring fault.
Is it possible to use a capacitor with a larger capacity?
Using a capacitor with a capacitance higher than the nominal (more than +10-15%) is not recommended. This will increase the starting current, overheat the compressor windings and may trigger the thermal protection relay. It is better to stick to the factory settings.
Why does a new capacitor immediately burn out?
There may be several reasons: power surges in the network, a faulty starting relay that does not turn off the winding after starting, or an internal short circuit in the compressor itself. A new part may also be defective.
How to distinguish a starting capacitor from a working one?
Visually they may be similar, but starting capacitors usually have a shorter lifespan of on/off cycles and often (but not always) lower capacity with the same dimensions. The main difference is in the markings: look for the words “Starting” or “Motor Run”.
Is it dangerous to leave a refrigerator with a faulty capacitor?
Yes, it is dangerous. Attempts to start with a faulty starting element cause a multiple increase in the starting current, which leads to overheating and eventual combustion of the compressor windings, the repair of which is often not economically feasible.