Checking the capacitor with a multimeter for functionality on the refrigerator

The refrigerator has stopped humming, the motor does not start or immediately knocks out machine, and the ice is already melting inside? Most often, in such a situation, the starting mechanism or capacitorthat ensures the start of the compressor engine is to blame. Diagnostics of this part does not require deep knowledge of electrical engineering, but requires care and compliance with safety precautions. In this article, we will look at how to check the functionality of a capacitor on a refrigerator with a multimeter, so that you can independently eliminate this malfunction.

A malfunction of the starting device is often confused with a breakdown of the compressor itself, which service centers can use to impose expensive repairs. Knowing the correct ring element, you will save time and money by making sure that the problem lies in the small plastic box. We will look at a step-by-step algorithm of actions, the necessary tools and typical mistakes of beginners when diagnosing.

The design and role of a capacitor in a refrigerator

In household refrigerators, such as Indesit, Beko or Atlant, capacitors play critical role in the motor starting circuit. They accumulate electrical charge and release it at the right moment, creating the phase shift necessary for rotating the rotor. Without a working starting capacitor motor windings receive power, but the torque is not sufficient to move the pistons.

Most often, a starting-type capacitor is used in the refrigerator, which comes into operation only for a split second at the time of start. If this element fails, the compressor either hums but does not start, or makes a clicking sound and goes silent. It is important to understand that capacity and operating voltage are key parameters that cannot be ignored when selecting a replacement.

Structurally, the element is a sealed housing, inside of which there are plates separated by a dielectric. Over time, the dielectric can degrade, losing its properties, which leads to a change in electrical capacitance or a complete short circuit. It is these changes that we will identify using a measuring device.

⚠️ Attention: Even after disconnecting the refrigerator from the network, the capacitor can retain a residual charge. Before touching the contacts, be sure to discharge it by shorting the terminals with a screwdriver with an insulated handle to avoid electric shock.

There are two main types of failures: loss of capacity (the element “dries out”) and breakdown (short circuit). In the first case, the engine will hum and try to start, in the second, the protection will trip or the fuse will blow. Understanding the physics of the process helps to quickly diagnose the problem.

Required tools and safety measures

To carry out high-quality diagnostics, you will need a minimum set of tools that any home craftsman will have. The main device will be multimeter (tester) capable of measuring resistance (Ohm) and capacitance (uF), if such a function is available. Without this device, it is impossible to carry out an accurate check, since visual inspection often does not give results.

You will also need pliers with insulated handles to disconnect the terminals and a screwdriver to remove the protective cover on the compressor. A flashlight is a good idea, since the motor-compressor area at the bottom of the refrigerator is often poorly lit. All work is carried out exclusively with power off.

• 🔌 A multimeter (digital or analog) is the main measuring tool.
• 🛠 Pliers and a screwdriver - for dismantling and disconnecting wires.
• 🔦 Flashlight - to illuminate the work area near the floor.
• 🧤 Dielectric gloves - additional protection when working with electricity.

Before starting work, make sure the floor is dry and your hands are not wet. Any moisture increases the risk of electric shock, even when working with low-voltage sections of the circuit, although the voltage in the refrigerator is standard - 220 volts. Compliance with these simple rules guarantees your safety.

Visual inspection and dismantling of the part

The first stage is always an external inspection. You can get to the condenser by removing the protective cover from the back of the refrigerator, near the compressor. The starter is usually mounted on the side or top of the motor and covered with a plastic or metal casing. Carefully remove the clips and remove the assembly.

Carefully inspect the capacitor body. If you notice swelling, traces of soot, electrolyte leaks or melted terminals, further checking with a multimeter may not be necessary - the part is clearly faulty. Such signs indicate thermal breakdown or overheating.

However, in most cases the case looks perfectly intact, although a break or loss of capacity has already occurred inside. Therefore, you cannot rely only on your eyes. Carefully disconnect the wires, first remembering or photographing the connection diagram so as not to confuse the contacts during assembly.

⚠️ Attention: Do not pull the wires sharply. Terminals can be fragile and wires can become dull over time. Use pliers while holding the base of the connector.

Checking the capacitor with a multimeter in ohmmeter mode

The most accessible way to check is to measure the resistance. Switch the multimeter to resistance measurement mode (2 MΩ or 200 kΩ limit). Connect the probes of the device to the terminals of the capacitor. If the element is working properly, the needle of the analog device or the numbers on the display should begin to show low resistance, and then smoothly increase to infinity.

This effect is observed because the capacitor is initially charged by the tester battery, passing current, and as the plates are filled with charge, the resistance increases. If the screen immediately lights unit (infinity) or zero, this is a sign of a malfunction. In the first case - an open circuit, in the second - a short circuit.

To carry out the test, it is important to observe polarity if the capacitor is polar (although the starting circuits of refrigerators often contain non-polar elements). When reconnecting the probes without first discharging, the device may not show anything, since the element is already charged. Therefore, start each new measurement by discharging the leads.

• 📉 The device shows “0” - there is a breakdown inside, the part must be disposed of.
• 📈 The device shows “1” (infinity) immediately - internal open circuit.
• 🔄 The resistance increases smoothly - the capacitor is working and accumulates charge.
• ⚡ The arrow twitched and fell - there may be a current leak or loss of capacity.

This method is good because it allows you to identify obvious defects. However, it will not tell you the exact capacity figure. If the capacitor has “dried up” and lost 50% of its power, but still retains the ability to charge, an ohmmeter can show it to be conditionally serviceable, although it will not be able to start the engine.

Measuring capacitance: accurate diagnostics

A more accurate method is to measure the actual capacitance and compare it with the rating indicated on the case. To do this, the multimeter must have a capacitance measurement mode (indicated Cx or by the capacitor icon). Switch the device to this mode and connect the element leads to the measurement sockets.

On the screen you will see a number in microfarads (uF or uF). Compare this value with the markings on the housing. A deviation within ±10-20% is considered acceptable. If 30 μF is written on the case, and the device shows 12 μF, such a capacitor will not be able to create the required starting torque for the compressor.

It is important to carry out measurements quickly so as not to overheat the element with the tester current, although this is unlikely in capacitance measurement mode. If your multimeter does not have such a function, you can use indirect methods or simply replace the part with a new one, since the cost of the capacitor is low.

Typical errors during testing

Beginners often make mistakes that lead to false conclusions. One of the most common is testing a capacitor that is not disconnected from the circuit. In this case, you measure the resistance of the entire circuit, including the motor windings, which gives incorrect results. Always desolder or disconnect the part completely.

Another mistake is touching the leads with your fingers while measuring. The human body has its own resistance, which can distort the readings of the device, especially at high measurement limits. Hold the probes only by the insulated part.

It is also worth mentioning the rush. If you do not wait for the needle or numbers to stabilize, you may mistake a slow-charging capacitor for a faulty one. Give the device time to react to the change in charge.

⚠️ Attention: Do not test the capacitor for a spark by closing the contacts of the charged element with a screwdriver. This method was relevant for old Soviet parts, but modern polypropylene capacitors can fail from such barbaric treatment.

Replacement and selection of a new element

If the diagnostics showed a malfunction, it is necessary to replace it. When purchasing a new capacitor, pay attention to three parameters: capacitance (uF), operating voltage (V) and overall dimensions. The voltage should be no less than that of the original (it can be more, but not less).

Dimensions are important, since the capacitor must fit into the standard seat on the compressor. If the new element is larger, it can be placed side by side by extending the wires, but make sure that it will not touch the hot compressor tubes.

• 🔍 The capacity should match within 5-10%.
• ⚡ Voltage: look for the marking 250V, 450V or higher.
• 🌡 Temperature: low-temperature series (up to -40°C) are important for refrigerators.
• 📏 Standard size: check whether the part will fit into the casing.

After installing the new part, reassemble everything in reverse order, turn on the refrigerator and listen. The engine should start smoothly, without buzzing or clicking. If the problem is not solved, perhaps the compressor itself or the relay is faulty.

Regular maintenance and timely replacement of worn-out elements will extend the life of your refrigerator. Remember that the starting capacitor is a consumable item, and its resource is limited by the number of switching cycles.