The situation when the refrigerator suddenly stops freezing, and a block of ice grows inside or, conversely, food begins to deteriorate from the heat, always takes you by surprise. Replacing the compressor is a complex technical process that requires not only theoretical knowledge about the structure of the refrigeration circuit, but also the presence of a specific tool. Many owners of household appliances, having seen the price tag for the services of a service center, are inspired by the idea of doing the repairs themselves, finding relevant video tutorials on the Internet.
However, it is worth immediately defining the limits of what is possible: if you do not have experience working with a blowtorch, vacuum pump and freon, the risk of completely ruining the unit tends to be one hundred percent. Motor-compressor is the heart of the system, and its incorrect installation will lead to rapid failure of even a new node. However, for those who have the skills of an all-rounder and are ready to strictly follow the technology, this task is completely solvable in a home workshop.
Before proceeding with dismantling, it is necessary to conduct a thorough diagnosis to make sure that the problem lies precisely in the mechanical or electrical part of the compressor, and not in a leak. freon or clogged capillary tube. Accurate diagnosis of a malfunction before starting work saves up to 50% of the budget that could be spent on purchasing unnecessary spare parts. In this article we will analyze in detail each stage, from preparing the workplace to the final launch of the system.
Diagnostics and selection of a new one unit
The first step is always a visual and auditory inspection of a working (or trying to work) refrigerator. If you hear the characteristic click of the start relay, followed by a humming sound that lasts a few seconds and then silence, this is a classic sign that motor cannot start or is stuck. Often in such cases, the compressor is hot to the touch, which indicates an attempt to idle or an overload of the windings.
To accurately confirm the diagnosis, it is necessary to “power” the unit directly, bypassing the standard starting relay and thermostat. This is done using a special diagnostic plug or a carefully assembled circuit with a capacitor. If, with a direct connection, the motor shaft does not even attempt to turn, but only hums and heats up, or there is dead silence when the tester tests the windings, then replacement is inevitable. It is also important to check the resistance of the windings: it must be within certain limits specified in the technical documentation for a specific model.
The choice of a new compressor is a critical moment, since there are practically no universal solutions here. It is necessary to focus not only on the overall dimensions and type of refrigerant (R134a or R600a), but also on the cooling capacity. Installing a more powerful unit will lead to short operating cycles and frequent starts, while a less powerful one will lead to constant overheating and inability to reach the desired temperature.
⚠️ Attention: When purchasing a compressor, pay attention to the type of oil. Synthetic oils (POE) are hygroscopic and quickly absorb moisture from the air, so you should open the packaging of a new compressor immediately before installation.
Below is a table of correspondence between popular models of compressors for household refrigerators, which will help you navigate when ordering spare parts:
| Refrigerator model | Refrigerant type | Power (W) | Installation features |
|---|---|---|---|
| Atlant KHT-170 | R134a | 115 | Bottom location, 4 tubes |
| Indesit NBS 18 | R600a | 95 | Requires precise gas dosage |
| LG GA-B409 | R600a | 105 | Compact body, low noise |
| Beko CN 327 | R134a | 120 | Standard paw mounting |
Necessary tools and workplace preparation
High-quality repairs are impossible without proper equipment. A DIY compressor replacement kit is significantly different from a standard box of screwdrivers. You will definitely need a gas torch (propane-oxygen or propane-air) with a set of solder. The use of tin-lead solders for refrigeration systems is unacceptable, since they cannot withstand pressure and temperature expansion; you need refractory solder containing silver, for example BCuP or its analogues.
The second critical element is a vacuum pump and a pressure gauge station (manifold). It is impossible to simply “bleed” air from the system, since moisture will remain in the circuit, which during operation will turn into an ice plug in the capillary tube or react with the oil, forming acid. The vacuum process should last at least 20-30 minutes until a deep vacuum is achieved.
You should also have in your arsenal:
- 🔧 Pipe cutter for copper (provides an even cut without burrs, unlike a hacksaw).
- 🔥 Solder paste or flux (only neutral, non-corrosive).
Do not forget to prepare a container for collecting old oil and rags. It is better to carry out work in a well-ventilated area or outdoors, since freon vapor displaces oxygen, and an open flame in a confined space is dangerous.
Dismantling the old one compressor
The process begins with completely disconnecting the refrigerator from the power supply. It is not enough to simply unplug the cord from the socket - make sure that access to the socket is blocked to prevent accidental activation by strangers. Next, you need to gain access to the engine compartment by removing the rear panel. In some models Indesit or Atlant it may also be necessary to remove the internal plastic cover of the evaporator if access to the tubes is limited.
The next step is to remove the old refrigerant. To do this, the copper tubes coming from the compressor (discharge and suction) are cut. The gas will come out with a characteristic hissing sound. After this, the compressor is disconnected from the electrical circuit: the terminal block is removed, the bolts securing it to the frame are unscrewed. It is important not to damage the ground wires.
To remove the old unit, it is often necessary to rock it, as the mounting bolts may be too tight or rusty. After removing the compressor, you need to tilt it and drain the used oil into a prepared container. The volume of drained oil must be measured in order to know how much new oil to pour into the new unit, although modern compressors are often already filled with the required amount.
⚠️ Attention: It is strictly forbidden to cut through the tubes while there is pressure in the system. Make sure that the gas has completely escaped before applying force to the copper lines.
After dismantling, carefully inspect the condenser (grid at the back of the refrigerator). If traces of oil or mechanical damage are visible on it, replacing the compressor will be pointless without repairing or replacing the condenser itself.
Installation and soldering of a new compressor
Installation of a new one motor-compressor begins with the preparation of pipes. The capillary tube and condenser/evaporator tubes must be cleaned of oxides with fine sandpaper or a special brush until shiny. A clean surface is the key to a sealed seam. The new compressor has sealed fittings that need to be carefully cut after opening them so that air is not sucked in.
The soldering process requires skill. The copper is heated evenly, and only then solder is introduced into the joint area. It is important not to overheat the tubes, especially where they enter the compressor housing, so as not to melt the internal rubber dampers. The seam should be smooth, without sagging or cavities. After soldering all connections (suction, discharge, capillary), the system becomes closed, but is still open to the atmosphere through the service pipe.
☑️ Preparation for soldering
Pay special attention to installing the filter-drier. It is mounted on the capillary tube before entering the evaporator. The filter must be installed quickly, immediately after removing the plugs, as it instantly begins to absorb moisture from the air. The flow direction indicated by the arrow on the filter housing must be strictly observed.
After assembling all copper connections, nitrogen pressure testing is performed. This allows you to identify micro-leaks that could have formed during soldering. The system is filled with nitrogen under a pressure of about 10-12 atmospheres, and the soldering points are washed. The appearance of bubbles will indicate a defect that must be eliminated before evacuation.
Evacuation and refrigerant charging
Evacuation is the stage of removing air and moisture from the circuit. A pressure gauge manifold is connected to the service pipe, to which, in turn, a vacuum pump is connected. Turning on the pump marks the beginning of the process. The pressure gauge needle should go into the “green” or even “red” zone (negative pressure). The pump operating time is at least 20 minutes, and for systems with R600a it is recommended to increase to 30-40 minutes.
After reaching a deep vacuum, the valve on the manifold is closed and the pump is turned off. You need to wait 10-15 minutes and check the pressure gauge needle. If the arrow remains in place, then the system is sealed. If the pressure increases, there is a fistula somewhere, and the procedure for finding a leak and soldering will have to be repeated.
Refrigerant charging is carried out strictly by weight. The refrigerator label (usually inside the chamber) indicates the exact number of grams. The use of a cylinder with scales or electronic scales under the cylinder is mandatory. “Refilling by eye” or by static pressure for household refrigerators is unacceptable and will lead to incorrect operation.
Why can’t refill “by eye”?
Excess freon will cause liquid refrigerant to enter the compressor, causing water hammer and destruction of the valves. A lack of freon will lead to overheating of the compressor and insufficient cooling. Accuracy down to the gram is critical for the durability of the system.
After refueling, the service pipe is clamped with a clip and sealed. This is the most crucial moment, requiring speed so as not to release the gas when disconnecting the hose.
First start-up and operation control
The final stage is turning on the refrigerator in the network. In the first minutes of operation, it is necessary to control the current consumed by the compressor using a current clamp. The current must correspond to the rating data for this model. The uniformity of heating of the condenser is also checked: it should heat up along its entire length, starting from the outlet of the compressor.
The temperature in the fridge compartment should begin to drop. Check the operation of the thermostat: when the set temperature is reached, the compressor should turn off. Cyclic operation is an important indicator of correct refueling and the absence of air pockets.
- 🌡️ Check the temperature in the freezer after 2-3 hours of operation.
- 🔊 Make sure there are no vibrations or extraneous knocks.
- 💧 Check for the absence of condensation on the outer walls.
If all parameters are normal, you can install decorative panels and return the refrigerator to the place of use.
⚠️ Attention: Technical characteristics and requirements for oils may change by manufacturers. Always check the official technical documentation (service manual) for your specific refrigerator model before starting work.
Frequently asked questions (FAQ)
Is it possible to replace the R134a compressor with a compressor from an old refrigerator?
No, this is strictly prohibited. Compressors for different types of freons (R12, R134a, R600a) have different winding designs, type of oil used and internal clearances. Using an unsuitable unit will lead to instant destruction of the system.
Is it necessary to flush the system when replacing a compressor?
Yes, if the old compressor burns out (the windings are broken), carbon deposits and acidic products of oil breakdown remain in the system. In this case, purging with nitrogen and washing with a special solvent is required, as well as a mandatory replacement of the filter-drier.
Why, after replacing the compressor, does the refrigerator freeze in only one corner?
Most likely, the capillary tube or filter-drier is clogged. This often happens if solder got inside during soldering or if the system was poorly evacuated and an ice plug formed.
How long does the entire replacement procedure take?
For an experienced craftsman with a ready-made tool and spare parts, the process takes from 1.5 to 2.5 hours. For a beginner doing this for the first time, it may take up to 4-5 hours, taking into account the search for tools and studying the instructions.