Failure of the main unit of the cooling system is always stressful for the owner of household appliances, but for a home craftsman it is also a challenge that requires accuracy and knowledge. Replacing the compressor is one of the most difficult operations in the repair of refrigeration equipment, as it requires not only mechanical skills, but also the ability to work with gas under pressure. Errors at the preparation or soldering stage can lead to repeated failure of the unit or even to an explosion of the system.
Before proceeding with dismantling, you must clearly understand that simply “re-soldering” the part is not enough. A complete vacuumization of the system and accurate refrigerant charge is required, the weight of which is measured in grams. Ignoring the technology will lead to the new motor burning out in the first minutes of operation due to lack of lubrication or overheating. In this article we will analyze all stages of the work, from selecting an analogue to the final launch.
⚠️ Attention: All work on replacing the compressor should be carried out only when the device is completely disconnected from the electrical network. Residual voltage in the circuit can be life-threatening.
Diagnostics and selection of a new compressor
The first step is always to ensure that the problem lies in the motor-compressor, and not in the thermostat, start relay or freon leak. If when you turn on you hear a beep, a click and the motor immediately goes silent, or if it hums but does not start, heating up at the same time, the windings are likely to break. It is also worth checking the resistance of the windings with a multimeter: it should be within the passport values for a specific model. turn-to-turn short circuit windings It is also worth checking the resistance of the windings with a multimeter: it should be within the specification values for the specific model.
When choosing a replacement, it is critical to take into account the power and type of refrigerant. Modern refrigerators often operate on R600a (isobutane), which is explosive, while older models use R134a or R12. Installation of a compressor designed for a different type of freon is unacceptable, since the oils and design features are designed for different pressures and chemical properties.
Pay attention to the markings on the nameplate. Power is usually stated in fractions of horsepower (e.g. 1/4 HP, 1/5 HP) or in watts. It is allowed to install an analogue with a power 10-15% higher than the original, but not lower.
- 🔍 Check the type of refrigerant on the nameplate of the old unit (R134a, R600a, R12).
- ⚡ Compare the power in Watts or horsepower (HP) to select the correct one analogue.
- 📏 Measure the mounting dimensions of the mounting feet so that the new motor fits into the standard places.
- 🔌 Make sure that the location of the starting relay and contacts matches or can be adapted.
⚠️ Attention: Never use compressors removed from other equipment without a thorough check tightness and cleanliness of internal tubes. There may be aggressive acid left inside from the combustion of old oil.
When purchasing a new unit, be sure to ask for a warranty card. Factory defects It is rare, but possible, and having documentation will save your finances in case of a defect.
The necessary tools and consumables
High-quality results are impossible without specialized equipment. A regular DIY kit won't be enough here. You will need a gas torch with a cylinder, preferably using a mixture of propane-butane or oxygen-propane, since the melting point of solder is high. To work with tubes, a pipe cutter is indispensable, which gives an even cut without the formation of chips inside.
Pay special attention to the choice of solder. For copper tubing, refractory solder with a silver content (usually 5%, 15% or 30%) is used. Using tin for soldering copper pipelines of a refrigerator strictly prohibitedas it does not withstand vibration and pressure, quickly losing its tightness. The flux must also be specialized and non-corrosive.
To vacuum and charge the system, a vacuum pump and a pressure gauge station are required. Without creating a deep vacuum, moisture will remain in the system, which, when frozen, will turn into an ice plug in the capillary tube, blocking the circulation of the refrigerant.
| Tool/Material | Purpose | Criticality |
|---|---|---|
| Gas burner | Heating copper to the melting temperature of solder | High |
| Pipe cutter | Even cut of pipes without chips | High |
| Solder with silver (15%) | Sealed connection of copper pipes | Critical |
| Vacuum pump | Removing moisture and air from the circuit | Critical |
| Gauge station | Pressure control during evacuation and charging | High |
Removing the old compressor
The process of removing a faulty unit begins with releasing the residual refrigerant pressure. To do this, you need to cut one of the copper tubes suitable for the compressor with wire cutters. If there is gas left in the system, you will hear a characteristic whistle. This should be done in a well-ventilated area, since freon vapor displaces oxygen.
After releasing the pressure, you can begin to disconnect the electrical wires and unscrew the mounting bolts. Be careful with the start relay; it may be fragile. Next comes the most crucial moment—soldering the tubes. Heat the joint with a torch evenly, being careful not to overheat the compressor housing itself or adjacent evaporator elements.
When the solder melts, carefully pull the tube with pliers. If it does not come off, heating must be continued. It is important not to use excessive force so as not to deform the thin-walled condenser or evaporator tubes located nearby.
- 🔥 Heat the connection on all sides to ensure uniform melting of the solder.
- 🧤 Use heat-protective gloves, since the metal holds a high temperature for a long time.
- 🔧 Secure the adjacent tubes with a tool so as not to damage them during dismantling.
After removing the old motor, inspect the cuttings of the tubes. If there are oxides or dirt on them, they must be cleaned or cut off again with a pipe cutter, leaving a margin of length for a new insert.
Preparation and installation of a new unit
Installation of a new compressor requires preliminary preparation. Remove the transport plugs from the fittings only at the last moment to prevent dust and moisture from getting inside. Compare the diameters of the suction and discharge tubes of the new motor with your existing copper system taps. Often the diameters do not match, and this is where insert adapters come to the rescue.
Insert the copper tubes into the compressor fittings. The gap should be minimal, but the tube should fit freely without jamming. The optimal planting depth is 10-15 mm. If the tube dangles, a tight connection will not work. In such cases, special adapters of different diameters are used.
The compressor is attached to the refrigerator frame through rubber shock absorbers. They dampen vibrations that, in direct metal-to-metal contact, would lead to rapid destruction of the tubes and noisy operation. Make sure that the motor is installed strictly vertically, as required by the design, and is not skewed.
⚠️ Attention: The compressor must not be installed upside down or on its side. In this position, the oil will not be able to return to the crankcase, which will lead to scuffing of the piston group and wedge after a few minutes of operation.
Technology for soldering copper joints
Soldering is a skill that comes with practice, but knowledge of the theory will prevent fatal mistakes. When heated, copper actively oxidizes, forming scale inside the tube. To prevent this, professionals flush the system with nitrogen during soldering. At home, nitrogen is often unavailable, so you need to heat it quickly and carefully, trying not to burn the metal.
Heat the joint with a torch until it is dark cherry in color. Touch the solder rod to the joint. If the temperature is sufficient, the solder will begin to melt and flow into the gap by capillary action. Do not pour solder directly onto the flame - it should melt from the hot metal of the pipes, and not from the fire of the burner.
Allow the connection to cool naturally. Do not blow on it or cool it with water, as a sudden temperature change can cause microcracks in the seam. After cooling, the seam should be smooth, without sagging or cavities.
☑️ Soldering quality control
Pay special attention to the filter-drier. This device removes moisture from the system. It is soldered last, as it is afraid of overheating. You cannot heat the filter housing - only the ends of the tubes. The heating time should not exceed 5-7 seconds.
Evacuating and charging with refrigerant
The most critical stage is removing air and moisture. Connect the hose from the vacuum pump to the service connection (usually located on the suction tube or filter). Turn on the pump and watch the pressure gauge. The arrow should go to minus, indicating a vacuum. For household refrigerators, vacuuming should last at least 30-40 minutes.
After turning off the pump, turn off the valve and wait 15-20 minutes. If the pressure gauge needle remains in place, the system is sealed. If the pressure begins to increase, it means that there is a micro-leak somewhere that needs to be found (with a soap solution) and eliminated by re-soldering.
Refrigerant is charged strictly by weight. The refrigerator label (usually inside the chamber or on the back wall) indicates the exact number of grams. Use electronic scales for the cylinder: weigh the cylinder, open the filling valve and close it when the weight decreases by the required value.
Filling accuracy is critical: a lack of freon will lead to undercooling, and an excess will lead to a sharp increase in pressure and a possible rupture of the condenser or breakdown of the compressor.Start-up and check performance
After refueling, disconnect the hoses and solder the service fitting. Plug in the refrigerator. In the first minutes of work, listen carefully to the sound: it should be smooth, without metallic knocks or whistles. Check the heating of the condenser (grid at the back) - it should heat up evenly, starting from the compressor.
Evaluate the operation of the evaporator inside the chamber. After 15-20 minutes, a “snow” coating or frost should appear on the evaporator tubes. If only part of the evaporator cools or only halfway, there may be moisture or air left in the system, or the capillary tube is clogged.
Why might there not be enough cold after replacement?
There may be several reasons: insufficient evacuation (water remains), incorrect dosage of freon, poor-quality soldering (the solder passage is narrowed) or a malfunction of the new compressor (rarely).
Let the refrigerator operate for several hours without loading food. Only after making sure of a stable temperature rise and automatic shutdown can the repair be considered complete.
Frequently asked questions (FAQ)
Is it possible to replace an R134a compressor with an R600a?
No, this is impossible and dangerous. Compressors for different refrigerants have different internal structures, different oils and different electrical power. In addition, R600a (isobutane) is explosive, and the system for it is made with a minimum number of connections and special safety requirements.
Is it necessary to change the filter drier when replacing the compressor?
Yes, definitely. The old filter is already saturated with moisture and oil breakdown products. If you leave the old filter, it will quickly release the accumulated moisture back into the system, which will lead to the formation of an ice plug in the capillary tube.
Why does the compressor get very hot after replacement?
Strong heating can be caused by several reasons: excess refrigerant in the system, the presence of air (poor vacuum), a malfunction of the new compressor or problems with ventilation (if the refrigerator is built-in). Also, the reason may be that the discharge tube is too long, creating excessive resistance.
Which solder is better to use: with or without silver?
For refrigerators, it is strongly recommended to use solder containing silver (for example, PSR-15 or imported analogues). Silver increases the fluidity of solder, its strength and resistance to vibration. Conventional brass solder without silver is less reliable in conditions of constant vibration of the compressor.