A sudden breakdown of the refrigerator is always stressful, because food supplies are at risk, and the wait for a repairman can last for several days. The first sign of a malfunction is often the absence of the characteristic hum of a running motor or, conversely, its endless operation without reaching the desired temperature. Self-diagnosis compressor allows you to quickly determine the scale of the problem and understand whether it is worth calling a specialist or whether it is easier to replace the unit.
Before taking active steps, you need to make sure that the problem lies precisely in the motor-compressor, and not in a banal lack of electricity or a burnt out light bulb. If the light in the chamber is on, but there is no cold, and the unit itself is silent or makes clicking noises, then the probability of failure of the motor windings is extremely high. In this article we will look at how to carry out accurate diagnostics without complex equipment. start relay or motor windings are extremely high. In this article we will look at how to carry out an accurate diagnosis without complex equipment.
It is important to understand that the compressor is the heart of the refrigeration circuit, and its serviceability depends on many factors. If, when you touch the body of a running compressor, you feel a strong tingling current, immediately disconnect the device from the network - this is a sign of breakdown of the winding insulation. Further operation of such a device is life-threatening.
Primary visual and sound diagnostics
Any professional diagnostics begins with a simple inspection and analysis of the sounds that a household appliance makes. Go to the refrigerator and listen: if you hear a quiet hum that ends abruptly with a click and repeats cyclically, this is a classic symptom of a faulty trigger mechanism or a jammed piston group. In normal operation, the motor should start smoothly and operate evenly.
Visually inspect the rear wall of the unit. There should be no traces of soot, melted wires or oily smudges on it. The presence of black carbon deposits on the tubes or the compressor body itself often indicates a short circuit in the windings or overheating due to prolonged operation in extreme conditions. Also pay attention to the integrity of the insulation of the supply cables.
Check the temperature conditions. If the compressor runs continuously without stopping for hours and the temperature in the chambers does not drop below +10°C, this may indicate a loss of performance. The piston group could be worn out, and the engine is simply not able to create the necessary freon pressure in the system, although electrically it is fully operational.
Necessary tools and safety measures
To carry out high-quality diagnostics, you will need a minimum set of tools, which can often be found in the garage or bought at the nearest hardware store. The main device will be multimeter (tester), which allows you to measure the resistance of the windings and check the integrity of the circuit. Without it, diagnostics will be only speculative.
⚠️ Attention! All work on disassembling and testing electrical circuits must be carried out only with the refrigerator completely disconnected from the network. Remove the plug from the socket before removing the casing.
In addition to the multimeter, you will need:
- 🔧 A set of screwdrivers (phillips and flat) for removing the protective casing.
- 🧤 Dielectric gloves for protection against residual voltage.
- 🔦 Flashlight for illuminating hard-to-reach places in the engine compartment.
- 🧹 Brush for cleaning contacts from dust and oxides.
Ensure good lighting of the work area. The engine compartment is often clogged with dust, which is a dielectric, but when combined with humidity can create conductive bridges. Before starting measurements, carefully clean the contacts and connectors with a dry rag or brush.
☑️ Preparation for diagnostics
Removing the protective casing and accessing the compressor
To get to the electrical part of the compressor, you need to remove the protective box located in the lower rear part refrigerator. It is usually secured with snaps or a few screws. Be careful not to damage the plastic fastening elements, as they become brittle from the cold.
After removing the casing, you will see a black metal compressor tank, to which copper tubes and an electrical cable fit. A plastic box is placed on the compressor terminals - this start-up protection relay. This is what we have to remove first to check the contacts and windings.
Carefully remove the relay. It can be fixed with a clamp-clip or simply sit tightly on three contact pins. Remember or photograph the position of the wires so that during assembly you do not confuse phase and zero. Do not pull the wires, hold only the plastic housing of the relay.
Nuances of fastening the relay
In some models of Indesit and Ariston refrigerators, the starting relay can be additionally fixed with a metal strip, which is screwed to the compressor housing. Don't forget to loosen this screw before dismantling.
Checking the starting relay and thermal relay
The starting relay is responsible for supplying a starting pulse to the motor winding, and the thermal relay (thermal protection) turns off the power when overheated. Often the breakdown lies precisely in these compact devices, but the motor itself remains intact. Visually inspect the insides of the relay: if the plastic is blackened or the contacts are melted, the device requires replacement.
The integrity of the thermal relay is checked using a multimeter in continuity mode. Apply test leads to the input and output contacts of the relay. If the device makes a beep or shows zero, the circuit is intact. Lack of response indicates an internal rupture of the bimetallic strip.
For a starting relay, installation orientation is also important. There is usually an arrow or inscription on the housing UPindicating the top position. Incorrect installation the relay can cause the compressor to not start or to operate under overload.
| Relay type | Principle of operation | Frequent malfunction | Test method |
|---|---|---|---|
| Posistor | Heating of the crystal with current | Destruction of the posistor | Visual inspection, continuity |
| Induction | Electromagnetic coil | Contact sticking | Checking the core stroke |
| Thermal | Bimetal plate | Open circuit of protection | Ring tester |
Diagnostics of motor windings with a multimeter
The most accurate way to check the condition of an electric motor is to measure the resistance of its windings. On the compressor body you will see three contacts, often marked with the letters C (Common), R (Run) and S (Start). The markings may differ in different models, so it is better to check the technical documentation or the diagram on the relay.
Switch the multimeter to resistance measurement mode (Ohm). Measure the resistance between pairs of contacts one by one. Typically, the sum of the resistances of the starting and working windings should be equal to the resistance between the extreme contacts. If the device shows infinity (1 or OL), it means that there is a break in the winding.
If the resistance is close to zero, this indicates interturn short circuit. Such an engine will not work, and when you try to turn it on, it will knock out the circuit breakers in the panel. Normal resistance values vary between 10-30 Ohms for the working winding and 30-50 Ohms for the starting winding, depending on the power of the model.
Checking for breakdown of the housing (short to ground)
One of the most dangerous faults is an insulation breakdown when voltage hits the metal body of the refrigerator. This not only disables the equipment, but also creates a real risk of electric shock for users. You can also check for breakdown using a multimeter.
Press one probe of the tester to any of the contacts of the motor windings, and the second to a place that has been cleared of paint on the metal body of the compressor or a copper tube. The device should show infinity (open circuit).
If the multimeter shows any resistance value or makes a squeak, then the insulation is broken. It is strictly prohibited to operate such a refrigerator. Even if it works temporarily after “tapping”, the risk of electric shock remains critical.
⚠️ Attention! Some modern inverter compressors have complex electronic components built into the housing. Their diagnosis with a multimeter according to the classical scheme may be ineffective or impossible without special tools.
Analysis of pressure and performance (pressure test)
If the electrical part of the compressor is working, but there is no cold, the problem may be in the mechanical part - the piston group. To check the pressure, a special service tool is required: pressure gauge station. This stage is already closer to professional repair.
A pressure gauge is connected to the process pipe of the compressor (usually a copper tube). When starting the engine, the gauge needle should rise quickly. For household refrigerators, a discharge pressure of around 6-10 atmospheres (bar) is considered normal, depending on the type of refrigerant (R600a or R134a).
If the compressor is humming, the current consumption is normal, but the pressure does not increase or grows very slowly, this indicates that the valves or piston group are worn out. The motor drives freon idling, without creating the necessary pressure drop for circulation in the system.
Why is it important to know the type of freon?
Isobutane (R600a) refrigerators operate at lower pressure than units using R134a freon. The pressure gauge readings must be interpreted taking into account the brand of refrigerant indicated on the label. tag.
Is it possible to check a compressor without a multimeter?
Without a multimeter, it is impossible to carry out an accurate diagnosis. You can only indirectly judge the malfunction by external signs: lack of startup, burnout of a light bulb when connected directly (for a short time!) or a characteristic burning smell. However, the “poke method” can finish off a working one. motor.
Why does the compressor start and immediately turn off?
Most often this is caused by a thermal protection relay. Reasons: jamming of the compressor, interturn short circuit, malfunction of the starting relay or voltage surges in the network. Also, the cause may be a freon leak, which is why the motor cannot start working. mode.
Is it worth changing the compressor yourself?
Replacing the compressor requires soldering copper tubes, evacuating the system and accurately filling the freon. Without special equipment and skills, it is impossible to do this efficiently. Replacing it yourself often leads to repeated failure in a short time.
What is the service life of the compressor? refrigerator compressor?
The average service life of modern compressors is 10-15 years. However, with constant overload, poor ventilation or power surges, this period can be reduced to 5-7 years. Manufacturers claim that inverter models are more durable.