What does a refrigerator engine look like: device, types and diagnostics

When looking for an answer to the question of what a refrigerator engine looks like, many users imagine a complex electronic device with microcircuits and displays, but the reality is much more mundane and mechanical. Externally, this unit is a massive, hermetically sealed black metal cylinder located in the lower rear part of the household appliance. It is this element, which is technically more correctly called compressor, that is the heart of the entire cooling system, forcing the refrigerant to circulate through the tubes.

If you look behind the back of a working unit, you will see that the motor does not just hang in the air, but is fixed on a special base using shock-absorbing springs or rubber gaskets. This design is necessary to dampen vibrations that occur when the piston group operates inside the housing. On the surface of the black casing you can often see stickers with technical information, which indicate the type of refrigerant, operating voltage and device model, which is critically important during diagnosis or replacement.

It is important to understand that a visual inspection of the external part gives only a general idea, since key processes occur inside the sealed flask. However, even by external signs, an experienced technician can determine the condition of the unit: swelling, traces of oil or excessive heating of the housing indicate serious problems. In this article, we will analyze in detail what this unit consists of, how different types of drives differ, and what to look for during a visual inspection.

⚠️ Attention: It is strictly forbidden to open the sealed compressor housing at home! There may be gas under high pressure inside, as well as oil vapors that are hazardous to health.

Appearance of the compressor: main elements

Looking at the refrigerator engine, the first thing that catches your eye is its characteristic shape - it is a flattened ball or cylinder, painted black. This color was not chosen by chance: black color best promotes heat transfer, which is extremely important for cooling a working mechanism. The metal casing is made of durable steel that can withstand internal pressure and protect moving parts from dust and moisture.

Three copper tubes come out from the bottom or side of the housing, which are an integral part of the hydraulic circuit. Two of them are usually located closer to each other, and the third can be placed separately or have a different diameter. Through these lines, freon gas is sucked from the evaporator and compressed gas is pumped into the condenser. The tightness of the connections between the tubes and the housing is the main sign of the health of the system; any traces of oil or dirt in these places indicate a leak.

Additional attachments are often located next to the main unit, covered with a plastic or metal box. This is a starting and thermal relay, which is responsible for starting the engine and protecting against overloads. It looks like a small box placed directly on the contact group of the compressor. It is this element that most often fails during power surges, and its replacement does not require depressurization of the system.

• 🔩 Sealed black steel casing that serves as a reservoir and radiator.
• 🔩 Three copper fittings (tubes) for connecting to the refrigerant circuit.
• 🔩 Automatic starting block (relay and thermal protection), fixed to the side or bottom.
• 🔩 Mounting eyes or studs with rubber shock absorbers for fastening to the frame.

Internal structure: what is hidden inside the casing

Although we cannot look inside without compromising the integrity of the casing, the structure of the refrigerator motor is well studied and standardized. Inside the black cylinder, in its lower part, there is the electric motor itself and the compressor mechanism, immersed in a special compressor oil. This oil is necessary to lubricate rubbing parts and remove heat, as well as to ensure additional tightness of the gaps between the piston and cylinder.

The electrical part is an asynchronous motor with a squirrel-cage rotor. The stator is mounted on internal springs, which also serve to suspend the entire internal structure, dampening vibrations. The rotor is mounted directly on the shaft, which drives the crank mechanism. When the shaft rotates, the piston makes a reciprocating motion, sucking in and compressing the refrigerant refrigerant.

In the upper part of the internal cavity there is a discharge valve, through which the compressed gas goes into the condenser. The design is assembled in such a way that the oil level always remains above the suction pipes, but below the exhaust pipes, in order to prevent water hammer and oil from entering the cooling system. Violation of this balance, for example, when storing the refrigerator in a horizontal position for a long time, can lead to breakdown.

Why does the compressor heat up?

During operation, the refrigerator engine heats up to 60-90 degrees Celsius. This is a normal phenomenon, since when the gas is compressed, the temperature rises sharply, and the winding of the electric motor also heats up. The casing is specially made black and often has fins or simply a large area for effective heat exchange with the surrounding air. If the temperature exceeds 100 degrees or the thermal protection turns off, this is a sign of a malfunction.

Differences between a conventional and inverter motor

Visually distinguishing a conventional compressor from inverter can be difficult, especially if you see them for the first time. Both types have similar sealed housing and dimensions. However, if you look closely at the labeling and technical documentation, you can find significant differences. Conventional models operate on an on-off principle, while inverter motors are able to smoothly regulate the speed of rotation of the shaft.

Inverter motors, such as the popular models from LG or Samsung, often have a more complex electronic control board built-in directly into the housing or located nearby. They are characterized by lower levels of noise and vibration, since they do not make constant starts at maximum speed. The service life of such units is, as a rule, longer, and energy consumption is lower due to the absence of starting currents.

The cost of inverter models is much higher, which is due to the complexity of production and the presence of rare earth magnets in the rotor design. When repairing such engines, they require special equipment for diagnostics, since it is more difficult to check them using standard methods. An ordinary user can notice the difference only by the nature of the operation: an inverter refrigerator hums barely audibly and almost constantly, without making sharp clicks when starting.

Characteristics table different types of compressors

To systematize information about the design of refrigerator engines, it is convenient to use a comparison table. It will help you understand what parameters are critical for different types of units and what to expect from their operation in domestic conditions.

The table shows that the evolution of engines is moving towards reducing noise and energy consumption. However, it is worth noting that conventional piston compressors remain more maintainable and cheaper to maintain. The choice of motor type often depends not only on the desire to save on electricity, but also on the requirements for quietness in the room.

Visual fault diagnosis

You can determine that there is something wrong with the refrigerator motor even before calling a technician, simply by carefully examining its appearance. The first warning sign is the presence of oily stains around the pipes or on the floor under the unit. Since the system is sealed, oil can only leak out together with freon through the hole formed, which indicates the circuit. depressurization contour.

Pay attention to the color of the metal in the area of ​​the fittings. If the copper tubes are coated with green oxides or show signs of corrosion, this may indicate a long-term leak or moisture in the system. It is also worthwhile to carefully (with the device unplugged) touch the housing: it should be warm, but not hot. Excessive heating of the upper part of the casing may indicate an interturn short circuit of the windings.

An important element of visual inspection is the condition of the starting relay. If traces of melting, soot, or a burning smell are visible on the plastic case, then most likely the problem lies in the starting system. In such cases, the compressor itself may be in good condition, but without replacing the relay it will not be able to start, which will lead to its eventual combustion.

Typical problems and their external manifestations

One of the most common problems is the so-called “wedge” of the compressor. Outwardly, it looks like the engine is trying to start: there is a hum, a relay click, and then silence again. If you touch the housing at this point, it may be hot. This indicates that the mechanical part is jammed and the rotor cannot turn. In some cases, the “bleeding” method helps, but it requires qualification.

Another common problem is a break or short circuit of the windings. It’s difficult to determine visually, but if you remove the cover of the starting relay and inspect the contacts, you can see carbon deposits or melted insulation of the wires going to the motor windings. The smell of burning insulation is a sure sign of an electrical malfunction inside the motor.

⚠️ Attention: If you hear a metallic knock or clanging inside the compressor when the refrigerator is operating, immediately unplug the appliance. This is a sign of destruction of the internal mechanical part, and further work will lead to complete failure of the unit.

It is also worth mentioning the problem of moisture saturation of the oil. If the refrigerator stood idle for a long time or was transported lying down, the oil could mix with the refrigerant or lose its properties. This may not have external signs, but engine operation will be accompanied by increased noise and overheating. In such cases, a complete oil change and evacuation of the system are often required.

Frequently asked questions (FAQ)

Is it possible to replace a black compressor with a different size?

Theoretically it is possible, but it is extremely undesirable without consulting an engineer. Refrigerator engines have different cooling capacities. If you install a more powerful motor, the system will not have time to release heat, and the discharge pressure will increase to critical. If it is weaker, the refrigerator will not freeze. In addition, the seats and diameters of the tubes may not match.

Why is the compressor hot to the touch, is this normal?

Yes, this is absolutely normal. During gas compression, the temperature inside the cylinders reaches high values. The compressor housing heats up to 60-90 degrees Celsius to effectively remove heat to the environment. You should sound the alarm only if it is red-hot (which cannot be seen on ferrous metal, but can be felt by the heat) or if the thermal protection is triggered.

How much does a refrigerator engine weigh?

The weight of a standard household compressor varies from 9 to 12 kilograms. The main part of this weight is the steel shell and copper winding of the motor. That is why, when transporting refrigerators, it is recommended not to tilt them excessively, so that oil does not get into the circulation circuit, although modern models often allow transportation lying down.

Is it possible to repair a compressor with your own hands?

Replacing the start relay, filter-drier or tightening contacts are operations available to a home craftsman. However, opening a sealed casing, replacing valves or a piston group at home is impossible without special equipment for soldering, vacuuming and refilling with freon. Such work is performed only in service centers.

The hum of the compressor has become louder, what should I do?

Increased noise can be caused by several reasons: wear of the bearings, loosening of the fastening bolts, vibration of the tubes against the housing or adjacent parts. Check to see if the copper tubes are touching each other or the cabinet wall. If the motor itself is humming and the sound is metallic, it is probably approaching the end of its life.