Failure compressor is perhaps the most serious and expensive scenario for the breakdown of a household refrigerator. If you hear that the engine is humming, but does not start, or the unit is silent, but it is already warm inside, there is a high probability that it is time to replace the “heart” of the system. Self-repair in this case requires not only technical skills, but also special tools, since the work involves refrigerants and high temperatures.
Before you begin dismantling the old unit, you must clearly understand that replacing a compressor is not just unscrewing the bolts. This is a complex technological process that requires evacuation of the system and precise dosage of freon. An error at any stage can lead to the fact that a new expensive unit will burn out in a few minutes or the system will quickly become clogged with moisture. Inverter models require an even more delicate approach and frequent programming.
In this article we will analyze all the nuances of the process: from diagnostics and selection of analogues to soldering technology copper tubes. You'll learn which tools are a must-have, which tools you can do without, and why sealing the system is a critical step that cannot be ignored. Carefully study the theoretical part in order to avoid fatal mistakes during practical work.
Diagnostics of the malfunction and choosing a new compressor
Before buying a new part, you need to make sure that this is the problem. Often, symptoms indicating a motor breakdown can be caused by a freon leak or a faulty start relay. If the compressor turns on for a few seconds and clicks as it turns off, it could be overheating or low voltage. However, if you hear a hum when you turn it on, but there is no start, and the motor housing is hot, most likely there is a winding or a wedge in the piston group. an interturn short circuit windings or wedge of the piston group.
Selecting a new spare part is an important step. You can’t just buy the first compressor you come across with similar dimensions. The key parameters are the refrigerant (R134a, R600a, R12), capacity in BTU/hr or W, and oil type (mineral or polyester). Using the wrong refrigerant or oil will destroy the seals and cause system failure. For older models, it may be necessary to search for analogues, as original spare parts may be discontinued.
⚠️ Attention: Never use compressors designed for one type of refrigerant with another type of oil without completely flushing the system. Mixing oils can cause a chemical reaction and the formation of acids that will corrode the insulation of the windings.
When choosing, pay attention to the type of start: RSIR (start winding), RSCR (with capacitor) or CSIR. The diameter of the fittings of the suction and discharge tubes is also important, although they often have to be welded to the standard. For inverter refrigerators LG or Samsung, replacing a conventional compressor with a linear or inverter requires re-soldering the entire electrical circuit and installing a control board, which is extremely difficult to implement at home.
Necessary tools and materials for work
Replacing a compressor is impossible without specialized equipment. A basic DIY kit will not work here, since the system requires working with gas under pressure and creating a deep vacuum. You will definitely need a kit for soldering copper pipes: gas torch (propane-butane or oxygen-acetylene), solder (silver or phosphorus-copper) and flux. The use of tin for soldering high-pressure pipes is prohibited, as it will not withstand vibration and pressure.
The second critical element is the vacuum pump and gauge station. Without evacuation, moisture and air will remain in the system, which will lead to the formation of ice plugs in the capillary tube and corrosion from the inside. You will also need a cylinder with freon of the required brand and scales for accurate filling, since filling “by eye” by pressure often leads to incorrect operation of the refrigerator.
Additionally prepare:
- A pipe cutter for copper (so as not to deform the tube);
- Valves for clamping the tubes (if it is not possible to bleed off all the gas at once);
- Nitrogen for purging (preferably, but not always necessary for simple repairs);
- Multimeter for checking circuits.
Preparation of the refrigerator and dismantling the old unit
The first step to a successful replacement is complete preparation of the workplace and the refrigerator itself. The unit must be disconnected from the power supply, defrosted and moved away from the wall, ensuring access from all sides. If there is still freon left in the system, it needs to be vented. This should not be done indoors - many refrigerants are heavier than air and displace oxygen, which is dangerous for breathing. It is best to carry out this operation outdoors or with strong ventilation.
After removing the protective casing (usually it is located at the bottom at the back), disconnect the electrical wires. Take a photo of the connection diagram or sketch it so as not to mix up the contacts during assembly. Disconnect the start and safety relay. Next, you need to cut through the copper tubes connecting the compressor to the condenser and evaporator. This should be done with a pipe cutter or wire cutters, trying not to flatten the ends, so that later it will be easier to insert them into the new compressor.
☑️ Checklist before dismantling
Unscrew the mounting bolts or nuts, holding the compressor to the frame. Sometimes it can be welded or glued, but most often rubber washers and bolts are used. Carefully remove the old motor, being careful as there may be oil remaining in it. Immediately assess the condition of the condenser: if it is heavily dirty or deformed, it is also better to clean it or replace it, otherwise the new compressor will work with overload.
Soldering technology and installation of a new compressor
Installation of a new unit begins with preparing the tubes. If the diameters of the new compressor tubes do not match the old ones, use adapters or carefully flare the ends. Before soldering, be sure to remove the plastic plugs from the fittings of the new compressor only at the moment of connection, so that dust and moisture do not get inside. Insert copper wire or use asbestos cord inside the tubes to prevent solder from flowing inside and blocking the channel.
The soldering process requires fast and reliable heating. The burner flame is directed to the junction of the tube and the fitting. When the copper heats up to a cherry color, add solder. It should melt from the heat of the metal, and not from the flame of the burner. A high-quality seam looks smooth and uniform, without sagging or cavities. Pay special attention to the filter-drier: it must be changed every time the system is opened, installing it in the direction of flow (arrow on the housing).
⚠️ Attention: When soldering, do not overheat the compressor housing. Heat can damage the internal insulation of the windings or melt the plastic components of the valve group. Use a damp rag to cool the housing near the seam.
After soldering all connections (discharge, suction, process tube for refilling), the system must be purged with nitrogen under pressure to remove oxides and possible debris. Then the process tube with an installed nipple or valve is sealed for subsequent filling. Only after checking the tightness (pressure testing with nitrogen for 20-30 minutes) can you proceed to evacuation.
Evacuation and charging with refrigerant
Evacuation is the most important stage on which the durability of the repair depends. Connect the pressure gauge station to the process tube and start the vacuum pump. The pressure in the system should drop to a value close to absolute vacuum (usually the pressure gauge needle goes below zero, in the blue zone, to -1 bar or -30 inHg). The pump must run for at least 30-40 minutes to evaporate all the moisture from the oil and the walls of the tubes.
After evacuation, close the station valve and turn off the pump. Leave the system under vacuum for 15-20 minutes. If the pressure gauge needle does not rise, then the system is sealed. If the pressure increases, there is a micro-leak somewhere that needs to be found (with a soap solution) and eliminated. Refilling with freon is carried out only after confirmation of tightness. Scales allow you to measure the exact amount of gas indicated on the nameplate of the refrigerator (usually 60-120 grams).
Why can’t you fill by pressure?
Refilling “by eye” by pressure on the pressure gauge often leads to errors, since the pressure depends on the ambient temperature. Excess freon will lead to liquid hydraulic shock and valve failure, and too little will lead to overheating of the compressor.
Refill in small portions, allowing the refrigerant to distribute. After refueling, solder the process tube (take a bite and seal the tip) or close the valve. Turn on the refrigerator and monitor the operation: the freezer should begin to gain cold, and the compressor should work cyclically, without overheating. The temperature of the compressor housing in the working area should not exceed 80-90 degrees.
Typical errors and refrigerant compliance table
Even experienced professionals sometimes make mistakes that nullify all efforts. The most common of them is neglecting to replace the filter drier. The old filter is already saturated with moisture and will not be able to protect the system, which will lead to the formation of acid and clogging of the capillary with ice. The second mistake is poor soldering, leading to leaks, and lack of evacuation, which causes corrosion inside the system.
When replacing a compressor, it is important to consider oil compatibility. Mineral oils (used with R12 freon) do not mix with synthetic oils (POE), which are used with R134a and R600a. If you change the type of compressor or refrigerant, the system must be thoroughly flushed with a special solvent.
| Refrigerant type | Oil type | Marking color | Evaporation pressure |
|---|---|---|---|
| R12 (Freon-12) | Mineral | White | Low |
| R134a | Synthetic (POE) | Light blue | Medium |
| R600a (Isobutane) | Mineral/Alkylbenzene | Red | Low |
| R404A | Synthetic (POE) | Orange | High |
Grounding is also often forgotten. The new compressor must be reliably grounded, as vibrations can damage the insulation, and a breakdown on the housing will become life-threatening. Check the integrity of the ground wire at each installation.
Frequently asked questions (FAQ)
Is it possible to replace an R134a compressor with an R600a?
Theoretically, it is possible, but this requires a complete flushing of the system, changing the oil and, often, replacing the condenser and evaporator, since they have different heat transfer and operating pressure. It is easier and more reliable to install the compressor using the same type of refrigerant indicated on the refrigerator nameplate.
How much does it cost to replace a compressor yourself?
The cost consists of the price of the compressor itself (from 3,000 to 8,000 rubles), the cost of the refrigerant, filter, solder and rental or purchase tools (burner, pump, station). If there are no tools, their purchase may exceed the cost of calling a technician.
Why does the new compressor get very hot?
The reasons may be an excess of freon, the presence of air in the system (poor vacuum), a malfunction of the capacitor, or incorrect operation of the start relay. Also, the compressor may heat up when operating in no-frost mode if the defrost channel is clogged or the heating element is faulty.
Does it need to change the oil in a new compressor?
No, new compressors are supplied already filled with the required amount and type of oil. You only need to drain it and fill in a new one if you are using a used compressor or changing the type of refrigerant.