Compressor failure is perhaps the most serious malfunction that the owner of household appliances may encounter. It is this unit that is the heart of the system, ensuring the circulation of refrigerant and maintaining a low temperature in the chambers. If you hear that the engine is humming but does not start, or, conversely, it clicks and goes silent, you will most likely need replacing a compressor. Independent replacement of this unit is possible, but requires not only plumbing, but also specific skills in working with copper tubes.
Before you begin dismantling old equipment, you must clearly understand the risks. Improper soldering can lead to freon leakage, fire, or complete failure of a new expensive part. Unlike replacing a light bulb or gasket, you'll have to deal with open flames and high pressure. However, if you are confident in your abilities and have the necessary tools, you can save a significant amount on the services of a service center.
In this article we will analyze in detail the process of how to re-solder a compressor, paying special attention to the nuances of working with refrigerant and the tightness of the system. You will learn how to prepare a workplace, which tools are required, and which can be replaced with analogues in an emergency. It is important to understand that the success of the operation depends on compliance with the technology at each stage, starting from draining the oil and ending with the final vacuum check.
Diagnostics of the malfunction and selection of a new unit
Before grabbing the burner, you need to make sure that the problem lies in the motor-compressor. Often the symptoms of a breakdown can be caused by a faulty start relay or thermostat. If, when you turn on the refrigerator, you hear a quiet hum, which after a few seconds is replaced by a click and silence, this is a sure sign that the motor is jammed or it has burned out. It is also worth checking the voltage in the network, since low voltage can prevent the engine from starting.
For accurate diagnostics, professionals use a multimeter to test the windings. The resistance between the contacts must be within certain limits, and between the winding and the housing it must tend to infinity. If you find a break or short circuit, then compressor repair is impossible, only replacement is required. You need to buy a new unit based on the model of your refrigerator and the type of refrigerant used.
Modern models often work on R600a (isobutane)which is explosive, while old Soviet and many modern units use R134a. An error in choosing the type of compressor can lead to incorrect operation of the system or even an emergency. Be sure to check the markings on the nameplate of the old device with the characteristics of the new one.
⚠️ Attention: If you change the type of refrigerant (for example, from R134a to R600a), you must completely recalculate the system parameters and change the filter-drier to the appropriate one. A simple one-to-one replacement without taking into account the characteristics of the oil and freon is unacceptable.
When choosing, pay attention to the power and overall dimensions. The new compressor should fit into its original position without deformation of the tubes and frame. It is also critically important to choose the right one filter drier, since it is responsible for removing moisture from the system, which can turn into ice and clog the capillary.
Necessary tools and workplace preparation
High-quality soldering of copper tubes is impossible without specialized equipment. The minimum set includes a gas burner with a cylinder (a mixture of propane-butane or oxygen-propane for higher temperatures), a pipe cutter, rolling pliers and a flanging kit. Using a hacksaw for metal is strictly prohibited, as it leaves chips that will inevitably get inside the system and disable it.
In addition, you will need tools for working with a vacuum. After soldering, the system must be evacurated (evacuated air) using a vacuum pump and a pressure gauge station. An attempt to start the refrigerator without vacuuming will result in the air remaining in the tubes and enclosing the capillary tube with ice or oxidizing the oil.
- 🔥 Gas torch and fuel cylinder to heat copper to the melting point of the solder.
- 🔧 Pipe cutter for clean cutting of copper tubes without formation burrs.
- 🧹 Soldering materials: solder (silver or copper-phosphorus) and flux (borax).
- 🛡️ Personal protective equipment: gloves, goggles and a respirator.
Prepare the workplace: it should be well ventilated, as combustion of flux and the possible release of freon residues create harmful fumes. Provide access to the rear of the refrigerator from all sides. Check in advance the serviceability of all tools, especially the tightness of the connections of the pressure gauge station.
Safety precautions and refrigerant drainage
Working with refrigeration equipment involves risks associated with both high pressure and the chemical composition of refrigerants. Before starting any work, the refrigerator must be disconnected from the power supply. If there is freon left in the system, it must be vented. This cannot be done indoors - refrigerants are heavier than air and can displace oxygen, and some of them form toxic phosgene when in contact with an open fire.
For safe drainage, it is best to puncture the fitting on the filter drier or service pipe by putting a hose on it that is led outside or into a powerful hood. If you are replacing the compressor on a model with R600a, be extremely careful: isobutane is explosive. In such cases, craftsmen often prefer to cut the tubes in a well-ventilated area so that the gas comes out quickly and does not have time to accumulate.
⚠️ Attention: Never try to unsolder the tubes while there is pressure in the system. This can lead to a sudden release of hot oil and freon, which can lead to burns and fire.
After bleeding the gas, you can begin dismantling the old compressor. Unscrew the fasteners, remove the protective casing (if any) and carefully disconnect the electrical wires, having previously photographed the connection diagram. Now you need to cut or saw through the copper tubes connecting the motor to the condenser and evaporator.
Removing the old compressor and preparing the tubes
The process of removing the old unit begins with carefully soldering the copper tubes. Heat the joint with a torch until it turns dark cherry and remove the solder. It is important not to overheat the tube itself, so as not to melt it, but not to underheat it, otherwise the solder will not flow. After the tube has cooled, remove the compressor from the refrigerator frame.
Now you need to prepare the tubes for installing a new motor. The ends of the tubes coming from the condenser and evaporator must be cleaned of oxides and old solder. Use fine sandpaper or a special pipe cleaner. The surface must be shiny and smooth to ensure reliable soldering.
If the length of the standard tubes is not enough for convenient soldering, they can be extended using copper tubes of a suitable diameter. However, try to minimize the number of joints, since every seam is a potential leak point. You need to bend the tubes carefully, using a pipe bender or your own hands, avoiding creases that will block the passage of the refrigerant.
What to do if the tubes are rusty?
If the steel tubes at the exit from the housing are heavily corroded, they must be carefully cut to bare metal and welded or soldered copper inserts. You cannot work with rust - the seam will be leaky.
Soldering technology and installation of a new compressor
Installation of a new compressor begins with the installation of a filter-drier. It is installed on the discharge pipe (outlet) of the compressor. Before soldering, make sure that the plugs on the new compressor and filter are removed just before connection to minimize the ingress of moisture from the air. The process of soldering copper to copper (or brass) requires the use of flux (borax) and solder.
Heat the connection evenly by moving the torch flame around the tube. When the metal reaches the desired temperature, touch the solder to the joint - it should melt and close the gap due to capillary effect. Don't pour solder on top of a cold tube; it will simply flow off. A high-quality seam looks smooth and shiny, without cavities or sagging.
After installing the filter and connecting the discharge tube, we move on to the suction pipe. Cleanliness and tightness are also important here. All connections must be made as quickly as possible so that the system does not have time to become saturated with moisture. After soldering all connections, the new compressor can be fixed in the frame in its original places, using new shock absorbers or gaskets.
☑️ Check before soldering
Evacuation and charging with refrigerant
After all solder joints have cooled, The most important stage begins - vacuuming. A pressure gauge station and a vacuum pump are connected to the service pipe (usually a process tube). The pump is turned on for 15-30 minutes to remove air and moisture vapor from the system. The pressure should drop to a deep vacuum.
After turning off the pump, close the valve and observe the pressure gauge needle for 15-20 minutes. If the arrow remains in place, then the system is sealed and there are no leaks. If the pressure begins to increase, it means that somewhere there is a microcrack or a poor-quality seam, and the leak detection and soldering procedure will have to be repeated.
Refrigerant charging is carried out strictly according to the weight indicated on the refrigerator nameplate. It is strictly forbidden to use cylinders without scales, since excess or lack of freon will lead to incorrect operation or breakdown of the compressor. For different types of freons, there are their own charging standards that must not be violated.
| Refrigerant type | Cylinder marking color | Oil type | Features |
|---|---|---|---|
| R134a | Light blue | POE (synthetic) | Hygroscopic, afraid of moisture |
| R600a | Red | Mineral | Explosive, small filling |
| R12 (old) | White | Mineral | Prohibited, ozone depleting |
| R404A | Orange | POE/PAG | High pressure, for freezers |
Startup and performance check
After refueling, you can perform a test run. Plug in the refrigerator and listen to the motor running. It should start with a smooth hum, without vibrations or extraneous knocks. After 10-15 minutes of operation, check the temperature of the condenser (grid at the back) - it should gradually heat up, starting from the compressor.
Be sure to check all solder joints for leaks using a soap solution. Apply foam to the seams and watch carefully for bubbles. Even a microscopic leak will eventually lead to loss of freon and spoilage of food.
⚠️ Attention: If the compressor runs too hot or does not turn off for a long time, there may be air left in the system or the amount of refrigerant is incorrect. In this case, repeated diagnostics are required.
Let the refrigerator run idle for several hours to ensure the stability of the on and off cycles. Only after successful testing can you download products. Remember that correct preservation of the system and high-quality installation is the key to long service life of the equipment.
Frequently asked questions (FAQ)
Is it possible to seal a refrigerator without a vacuum pump?
Theoretically, some craftsmen use the freon pressing method, but this is extremely unprofessional and does not guarantee the removal of moisture. The moisture in the system will turn into an ice plug in the capillary, and the refrigerator will stop freezing after a couple of days or weeks. Evacuation is a mandatory step.
Which solder is best to use for soldering copper tubes?
Copper-phosphorus solders (for example, PMF-7) are ideal for copper-copper connections, since they do not require flux and have a melting point lower than that of silver. To solder copper to steel (for example, a compressor discharge tube), silver solder and flux are required.
Why does a new compressor get hotter than the old one?
This may be due to several factors: excessive freon charging, the presence of air in the system, a malfunction of the new unit itself, or insufficient cooling (poor rear ventilation). Also, the new motor may have different energy efficiency.
How long do you need to hold the vacuum?
The optimal operating time of the vacuum pump is from 30 minutes to 1 hour, depending on the volume of the system and the power of the pump. It is critically important not only to pump out the air, but also to allow the moisture to evaporate at low pressure.
Can I use an old filter drier?
Absolutely not. The filter drier is a disposable item. After opening the system, it instantly absorbs moisture from the air and loses its properties. Installing an old filter will negate all repair efforts.