Sudden When your refrigerator stops working, it often comes as an unpleasant surprise, especially when there are perishable foods inside. In most cases, the cause of the breakdown is compressor, which is the “heart” of the entire refrigeration system. Understanding the principles of its operation and the ability to carry out initial diagnostics can save you from an expensive call to a technician or, conversely, help you make the right decision about the need for professional intervention.
Before taking active steps, you must clearly understand the risks associated with electricity and refrigerants. DIY Repair of a refrigerator compressor is possible at the initial stages of diagnostics or when replacing attachments, but it requires strict adherence to safety precautions. Incorrect actions can lead to electric shock or damage to the sealed circuit.
In this article we will analyze the design of the motor-compressor, methods for identifying faults and the step-by-step process of replacing the unit. You will learn what tools are needed for the job and how to distinguish between a breakdown of the compressor itself and a failure of the start relay. A competent approach will save your budget and restore the functionality of your equipment.
Design and principle of operation of a motor-compressor
The compressor is a sealed block, inside which an electric motor and a piston group are located. All these elements are immersed in oil and sealed in a metal casing, which ensures low noise levels and no freon leaks. The electric motor drives the shaft, which compresses the refrigerant through the connecting rod-piston group, forcing it to circulate through the system.
The key elements of the external part are starting and thermal relay. They are responsible for starting the engine and protecting the windings from overheating. Modern models often use an inverter control system, where the shaft speed is controlled by an electronic unit, which makes diagnostics more complex compared to classic linear models.
What is the difference between a linear and inverter compressor?
The linear compressor operates on the “on-off” principle, reaching a set temperature and turning off. The inverter operates constantly, but changes power, which ensures quieter operation and stable temperatures, however, such units are sensitive to voltage surges and are more difficult to diagnose without special tools.
The tightness of the housing is both an advantage and a limitation. If mechanical destruction of the piston group or combustion of the windings occurs inside, such a compressor is usually not repaired, but replaced entirely. Opening the casing is possible only in specialized workshops, followed by welding and vacuuming of the system.
Main signs of a compressor malfunction
You can determine that the problem lies in the compressor by a number of characteristic signs. Often the refrigerator simply stops freezing, but the light inside is on. However, the lack of cold can also be caused by a freon leak, so it is important to conduct a comprehensive check.
Pay attention to the sounds the unit makes when trying to start. Humming, clicking or complete silence may indicate different stages of failure. It is also worth checking the heating of the housing: if the motor is hot, but does not start, the thermal protection may have tripped or an interturn short circuit has occurred.
- 🔊 The refrigerator hums, but does not start, periodic clicks of the relay are heard.
- 🔥 The compressor gets very hot within a few minutes of operation.
- ⚡ When connected to the network, the circuit breakers immediately knock out or the fuse blows.
- ❄️ The unit operates continuously without turning off, but the temperature in the chambers does not drop below +10°C.
It is important to distinguish between symptoms. If the motor hums for 5-10 seconds, then a click is heard and it goes silent - most likely the piston is jammed or the start relay is faulty. If there is silence and a cold case, the problem may be in the electrical circuit or the relay itself.
Diagnostics: checking the start relay and windings
The first step in repairing a refrigerator compressor with your own hands should be to check the start relay. This is an inexpensive part that often fails before the motor itself. To access it, you need to remove the back cover of the refrigerator (in some models access from below) and disconnect the plastic box covering the contacts.
After removing the relay, inspect it for melting, cracks or a burning smell. There may be an inductor or a posistor inside, which are subject to wear. Ring the contacts with a tester: in a certain position they should ring, when turned over, they should open (for a relay with a coil).
☑️ Diagnostics of the starting relay
If the relay is working properly, proceed to checking the windings of the compressor itself. There are usually three contacts on the motor body: common (C), starting (S) and working (R). It is necessary to measure the resistance between them. Normal readings are considered to be values from 10 to 30 ohms between working and common, and slightly higher between starting and common.
⚠️ Attention: If the multimeter shows a resistance close to zero or, conversely, infinity (open) between any two contacts of the windings, the compressor is faulty. It is also strictly forbidden to touch these wires when the equipment is connected to the network.
Pay special attention to checking for “breakdown”. One multimeter probe is placed on the contact, and the second is placed on the copper tube of the compressor, which has been stripped of paint. The device should show infinity. The appearance of any numbers indicates a violation of the insulation, which makes operation dangerous.
Necessary tools and preparation for replacement
If diagnostics have confirmed the need to replace the compressor, you need to prepare the workplace and tools. Replacing a sealed unit is a labor-intensive process that requires not only mechanical skills, but also special equipment for working with refrigerants.
You will need a set of wrenches, pliers, side cutters, and possibly a pipe cutter if sections of copper tubing need to be replaced. However, the most important tool will be a torch for soldering copper pipes and a vacuum pump with a pressure gauge station.
| Tool | Purpose | Importance |
|---|---|---|
| Multimeter | Checking the windings and relay | Critical |
| Gas burner | Soldering of copper pipelines | Critical |
| Vacuum pump | Removal of moisture and air from the system | Critical |
| Gas station | Pressure control and freon charging | Critical |
It is also necessary to purchase a new compressor, completely similar in power and type of refrigerant (R134a, R600a) old. Using the wrong model will lead to incorrect operation or rapid failure of the entire system.
Step-by-step instructions for replacing the compressor
The replacement process begins with completely disconnecting the refrigerator from the power supply. After this, you need to carefully unsolder the copper tubes going from the condenser and evaporator to the compressor. Be careful: when heated, gas may be released, so ensure good ventilation of the room.
Remove the old compressor by unscrewing the mounting bolts or cutting off the shock absorbing bushings. Install the new unit in place, securing it so that vibration is not transmitted to the refrigerator body. Connect the tubes, but do not solder them completely yet.
The next step is soldering the connections. Use solder and flux intended for refrigeration equipment. After sealing the circuit, it is necessary to connect the vacuum pump to the service connection and pump out the air for 30-40 minutes. This will remove moisture that, if frozen, could clog the capillary tube.
⚠️ Attention: Filling the refrigerator with freon must be done strictly according to the weight indicated on the manufacturer's nameplate. Excess or lack of refrigerant will lead to improper operation of the compressor and possible freezing or insufficient cooling.
After evacuation, the system is charged with refrigerant through a filling station. Then the service pipe is sealed. Turn on the refrigerator and check the operation: the condenser (grid at the back) should warm up evenly, and cold should appear in the freezer.
Common mistakes during self-repair
Independent repair of refrigeration equipment is full of nuances, ignoring which reduces efforts to zero. One of the most common mistakes is an attempt to start a “jammed” compressor by applying increased voltage or mechanical force. This is almost guaranteed to lead to the final destruction of the mechanism.
Another mistake is neglecting to replace the filter-drier. This small element, located at the outlet of the condenser, collects moisture and dirt. When replacing a compressor, it must be changed, since the old filter is already saturated with moisture and will not be able to protect the new system.
- 🚫 Lack of vacuuming before filling with freon.
- 🚫 Using regular solder instead of refractory solder for refrigeration pipes.
- 🚫 Attempt refilling “by eye” without scales and pressure gauges.
- 🚫 Ignoring cleanliness in the system (dust getting inside the tubes).
Also, do not forget about safety. Freon, although considered safe for humans in household concentrations, can form toxic compounds upon contact with an open flame. Work in a ventilated area and avoid smoking near the soldering area.
Is it possible to replace a compressor without a vacuum pump?
Theoretically, some craftsmen use the method of “blowing” with freon itself, displacing the air. However, this method does not guarantee the removal of moisture, which is the main enemy of the refrigeration system. Without a vacuum pump, there is a high risk of an ice plug forming in the capillary tube a short time after repair.
Why may a new compressor not start?
There may be several reasons: a faulty start relay (often included in the kit, but may be defective), lack of freon in the system (pressure sensors prevent the motor from starting), or an electrical problem in the control circuit. It is also possible for the new unit to jam due to prolonged storage in the wrong position.
How long does the compressor last after replacement?
The service life of a new compressor directly depends on the quality of installation. If the system has been well evacuated, the correct materials have been used, and cleanliness has been maintained, the unit will last the period stated by the manufacturer (usually 10 years or more). Dirt and moisture shorten the life of the compressor to several months.
Is it dangerous to change the compressor yourself?
The work involves high pressure and electricity. Incorrect soldering can lead to a fire, and poor-quality filling can lead to a cylinder explosion or pipe rupture. If you do not have experience working with gas and soldering, it is better to entrust this task to professionals.