Failure compressor is one of the most serious and expensive breakdowns in a refrigerator, often comparable in price to purchasing new equipment. However, for those who have the skills to work with power tools and understand the principles of operation of electric motors, replacing the unit yourself can be a way to significantly save your budget. The process requires not only technical skill, but also strict adherence to safety precautions, since the work is carried out with high voltage and refrigerant.
Before proceeding with the dismantling of the old motor, you need to make sure of the final diagnosis, since often the reason for the silence of the refrigerator is not itself engine, but the output The start relay or thermostat is faulty. If you have determined for sure that the compressor has burned out or jammed and decided to replace it, you will need a new unit that is completely identical in power, type of refrigerant and overall dimensions. Incorrect selection of spare parts can lead to incorrect operation of the system or repeated failure of the equipment in the shortest possible time.
In this article we will analyze in detail the stages of preparation, dismantling, soldering of copper tubes and electrical connection of the new engine. Attention: this material is for informational purposes only, and if you are not sure If you can, it is better to turn to professional craftsmen licensed to work with freon. Improper sealing of the system or errors during soldering can lead to gas leakage and loss of product load.
Fault diagnosis and preparation of tools
The first step before replacing the engine is a final check of its performance in order to eliminate errors in the diagnosis. Often equipment owners blame the compressor when the problem lies in an open circuit of the thermostat or a malfunction starting relay. Test the motor windings with a multimeter: the resistance between the starting and operating windings should be within normal limits, and the resistance between the housing and the windings should tend to infinity, which indicates that there is no breakdown to the housing.
To carry out replacement work, you will need a specific set of tools, which is not always available in your home arsenal. The main tool will be a torch for soldering copper tubes, running on propane-oxygen or propane-butane, since ordinary solder will not provide the necessary tightness and strength of the connection. Also necessary vacuum pump to remove air and moisture from the system, a pressure gauge station for monitoring pressure and refilling freon.
Don't forget to prepare tools for the mechanical part of the work: a set of open-end wrenches, pliers, wire cutters, screwdrivers and, preferably, a pipe cutter to avoid the formation of chips inside copper tubes. Chips that get into the system can instantly clog the capillary tube, which will require repeated disassembly and flushing of the circuit. All work must be carried out in a well-ventilated area, away from open flames, except for the burner itself.
⚠️ Attention: Before starting any work, be sure to unplug the refrigerator from the power supply and remove the plug from the socket. Working with live electrical components is fatal.
☑️ Tools for replacing the compressor
Removing the old compressor and preparing the place
The process of removing the old engine begins with access to the rear refrigerator. Remove the protective cardboard or metal panel covering the engine compartment. Before disconnecting any wires, take a photo of the connection diagram or sketch it so that when installing a new unit you do not mix up the contacts. This is especially important if you are changing the engine for the first time and do not remember the location of the terminals.
The next step is bleeding the refrigerant. If freon remains in the system, it must be carefully released by cutting the filling tube or cutting off one of the copper lines with pliers. Freon heavier than air and can displace oxygen, so ensure good ventilation in the room. After the gas has escaped, you can begin to unsolder the copper tubes from the compressor.
Use a torch to heat the soldering area until cherry-colored, then carefully disconnect the tubes. Do not forcefully pull them until the solder is completely melted to avoid deforming the copper. An old compressor usually has three tubes: one suction (large diameter) and two discharge (smaller diameter), or one discharge and one process, sealed from the factory. After unsoldering the tubes, unscrew the mounting bolts holding the engine to the frame and remove it.
Clean the installation site from dust, old paint and, if they interfere with the tight fit of the new unit. Check the condition of the rubber shock absorbers on which the motor is mounted: if they have lost their elasticity or are cracked, it is better to replace them, as they dampen vibrations during operation. The new compressor must be installed strictly in the same position as the old one, usually vertically, so that the oil circulates properly inside the system.
Why can’t you turn the compressor over?
Hermetically sealed compressors are filled with oil, which lubricates the rubbing parts. If tilted or turned over strongly, oil may flow into the refrigerant circuit, which will lead to water hammer and failure of the new engine upon first start-up.
Electrical connection diagram of the engine
The electrical part of the replacement is critically important, since an error in connecting the windings will lead to instantaneous combustion of the new engine or its failure to start. On the body of each compressor there is a terminal marking, usually indicated by the letters C (Common - common), R (Run - working winding) and S (Start - starting winding). In some models of domestic refrigerators, the marking may be digital or alphabetic Cyrillic, for example, O, R, P.
A starting relay is connected to these terminals, which supplies a pulse to the starting winding only at the moment of start, and then opens the circuit. If you connect the wires incorrectly, for example, apply 220V voltage directly to the starting winding, it will burn out in a split second. Therefore, the connection diagram must be reproduced exactly as it was on the old motor, taking into account the color marking of the wires.
The table below shows the standard color marking of wires for the most common types of compressors, but always check the technical documentation of the specific model:
| Winding type | Designation on the diagram | Wire color (standard) | Function |
|---|---|---|---|
| General | C or O |
Red or White | Power supply of both windings |
| Working | R or P |
Green or Blue | Main operation of the engine |
| Start | S or P |
Black or Yellow | Rotor start |
| Grounding | PE |
Yellow-green | Protection against electric shock |
When connecting, use new terminal clamps if the old ones are oxidized or burnt. Poor contact in the power circuit leads to heating of the connection, melting of the insulation and possible fire. After connecting the wires, carefully place them in bundles, secure with zip ties and make sure that they do not touch hot parts of the compressor or sharp metal edges.
Soldering copper tubes and sealing the system
The mechanical connection of the new compressor to the cooling system is carried out by soldering copper tubes. This is one of the most critical stages, requiring skill in working with an open flame. The tubes must be clean and free of grease. Before soldering, remove the plastic plugs from the nozzles of the new compressor only at the last moment to prevent moisture and dust from getting inside.
Heat evenly by rotating the burner around the connection. Use solder containing silver, which provides high strength and tightness of the seam. The melting point of silver solder is about 700-800 degrees Celsius, which is higher than that of ordinary tin, so it is important not to overheat the copper so that it does not leak. The solder should flow into the gap between the tube and the nozzle under the action of capillary effect, and not just spread on top.
Pay special attention to the process tube, through which vacuuming and filling will subsequently be carried out refrigerant. It must be of sufficient length to connect the pressure gauge station hose. After soldering all connections, allow the copper to cool naturally, do not pour water on it, as a sudden temperature change can cause cracks in the seams.
⚠️ Attention: When soldering, be sure to use a nitrogen purge or keep the flame minimal to avoid the formation of an oxide film inside the tubes. Copper oxides entering the system can clog the filter drier and capillary tube.
Evacuation and refrigerant charging
After the mechanical and electrical installation of the new engine, you cannot simply plug in the refrigerator. Air containing moisture remains inside the copper tubes. When the refrigerator operates, moisture freezes in the capillary tube, forming an ice plug that blocks the circulation of freon. In addition, the air increases the pressure in the system, increasing the load on the compressor.
To remove air and moisture, a vacuum pump is connected to the process tube. The pumping process should last at least 30-40 minutes until the pressure gauge needle shows a deep vacuum. Only after this the system is considered ready for charging. Vacuuming - this is a mandatory step, skipping which is guaranteed to lead to breakdown in the near future.
Refrigerant is charged strictly according to the weight indicated on the nameplate of the refrigerator (usually on the back wall or inside the chamber). You need to use the type of gas for which the compressor is designed (R134a, R600a, R12). An excess or lack of freon will disrupt heat transfer: in the first case, the refrigerator will freeze poorly, in the second, the compressor will work non-stop, trying to gain temperature.
First start-up and performance check
After completing all connection and filling work, you can proceed to testing. Plug in the refrigerator and listen to the startup sound. The engine should start with a characteristic hum, without clanging, knocking or whistling. If you hear a metallic knocking sound or excessive vibration, the engine may be installed unevenly or the internal shock absorbers may be damaged.
Check the heating of the compressor: during the first 15-20 minutes of operation it may heat up, but should not become too hot to hold your hand. Also check the tightness of all solder joints using a soap solution: apply foam to the seams and watch for the appearance of bubbles, which will indicate a gas leak.
Evaluate the quality of cooling. After 30-40 minutes of operation, frost should appear on the freezer compartment, and the temperature in the refrigerator compartment should drop. If the refrigerator runs for more than an hour, but there is no cold, the system may be clogged or the amount of refrigerant has been incorrectly calculated. In this case, repeated diagnostics are required.
Frequently asked questions (FAQ)
Is it possible to replace the compressor with a larger one? powerful?
Theoretically it is possible, but this is highly not recommended. A more powerful motor will create excess pressure in the condenser, which is not designed for such a load, which can lead to rupture of the tubes. In addition, the refrigerator's automation (thermostat, relay) may not work correctly with another engine.
Why does the new compressor get very hot?
Heating to 70-90 degrees for a compressor is a normal phenomenon, since it compresses gas, which is physically accompanied by the release of heat. You should sound the alarm if the engine gets red hot or there is a smell of burnt insulation coming from it.
Is it necessary to change the filter-drier when replacing the motor?
Yes, replacing the filter-drier is mandatory for any opening of the system. The old filter is already saturated with moisture and will not be able to clean the new refrigerant from residual moisture and acids, which will quickly damage the new compressor.
How long does it take to cool the compressor after soldering?
Allow the system to cool naturally for 15-20 minutes before starting evacuation. Sharp cooling with water is prohibited, as this creates thermal stress in the metal.