Restoring the functionality of a refrigeration unit Biryusa after the motor-compressor fails is a task that requires not only technical skills, but also strict adherence to safety rules. Replacing this unit is the most difficult procedure in household repairs, as it involves working with high voltage electricity and refrigerant. Before starting any manipulations, you must clearly understand that incorrect connection can lead to final breakdown of the unit or even fire.
Modern models Biryusa are often equipped with compressors from various manufacturers, including Danfoss, Secop or domestic ATLANT. The basic connection diagram is similar, but there are nuances in the length of the tubes, the type of starting relay and the number of turns of the windings. Ignoring these parts when installing a donor or a new unit is fraught with overheating and rapid failure of the entire cooling system.
In this article we will analyze in detail the process of preparing, dismantling the old unit and installing a new compressor. You will learn how to correctly identify contacts, solder copper tubes and perform the initial startup. Remember that to carry out this work you will need specialized tools, in particular, a brazing torch and a vacuum pump.
Fault diagnosis and preparation for work
Before you begin replacement, you need to make sure that the problem lies in the compressor, and not in the start relay or thermostat. Often, users mistakenly change a working motor, when it was enough to replace a cheap relay. Primary diagnostics include a visual inspection for melting and testing the windings with a multimeter. If the resistance between the contacts tends to infinity or, conversely, to zero, then there is a break or an interturn short circuit.
For safe work, you will need to prepare the workplace. It should be well lit and ventilated, since the soldering process is accompanied by the release of gases, and a possible leak of freon requires air circulation. It is also necessary to purchase in advance a new compressor that matches your model Biryusa, and components: a filter drier, a start-up relay and copper solder.
⚠️ Attention: Before starting work, be sure to disconnect the refrigerator from the power supply! Don't rely on the thermostat alone—unplug the cord. Residual voltage in capacitors can be dangerous; let the equipment stand turned off for about 30 minutes before disassembling.
Prepare the following tools: pliers, wire cutters, a gas burner with a cylinder, a set of keys and, preferably, a vice for fixing the unit. If you plan to use a compressor from another refrigerator model (donor), make sure that its power and cooling capacity correspond to the volume of your chamber Biryusy. A discrepancy between the parameters will either lead to underfreezing of the products or to constant wear and tear of the motor.
Removing the old compressor and preparing the pipes
The process of removing the faulty unit begins with access to the bottom of the refrigerator. Remove the rear metal panel covering the engine compartment. In some models Biryusa you may also need to remove the plastic casing that protects the electrical part. Carefully disconnect the wires from the start relay and grounding, having previously photographed the connection diagram so as not to confuse the colors during assembly.
The next stage is working with copper tubes. You need to cut the suction and discharge tubes at a distance of 10-15 cm from the compressor housing. This must be done carefully so that chips from the cutters do not get inside the system. The remaining ends of the tubes coming from the condenser and evaporator must be immediately plugged with special caps or simply clamped to prevent moisture and dust from entering. Moisture in the system is the main enemy, which turns into an ice plug and disables the unit.
Remove the compressor, by unscrewing the mounting bolts or cutting off the shock absorbing bushings. Be careful: compressor oil remains inside the old motor and in the pipes, which can leak onto the floor. Prepare a rag or container in advance to collect technical fluids. After removing the unit, inspect the condition of the condenser grille and pipelines for mechanical damage or corrosion.
☑️ Tools for dismantling
Connection diagram and contact marking
The most crucial point is the correct connection of the electrical part. On the body of each compressor, be it Biryusa-6 or more modern models, there is a contact group of three terminals. They can be designated by letters or numbers, but the standard marking is as follows: S (Start) - starting winding, R (Run) - working winding, C (Common) - common contact. In some cases, markings 1, 2, 3 are used, where the decoding must be found in the technical documentation.
The starting relay is placed directly on the contacts of the compressor. It is important to install it in the correct position, indicated by the "UP" or "UP" arrow. Inside the relay there is a starting capacitor and a thermal release, which provide engine starting and overload protection. If you mix up the contacts of the starting and working windings, the compressor will hum, overheat and the thermal protection will trip, or the winding will burn out.
⚠️ Attention: Never turn on the compressor without the starting relay connected! Direct supply of voltage to the windings will cause a short circuit and instantaneous failure of the unit.
To check the correct assembly, you can use a multimeter in resistance measurement mode. Between the common contact and the working winding, the resistance should be the smallest, between the common and starting winding - average, and between the starting and working winding - total. If the readings differ from this logic, check the integrity of the windings again. Also make sure that there are no oxides on the contacts, which can increase the contact resistance.
What to do if the contacts do not match the relay?
If you purchased a universal relay or a relay from another manufacturer, the shape of the contacts may not match. In this case, you cannot bend the contacts by force. It is necessary to carefully replace the block on the relay, moving the wires in accordance with the markings S, R, C. Make sure that the relay sits tightly on the terminals and does not dangle during vibration.
Soldering copper tubes and installing a filter
Mechanical connection of tubes is not used in refrigeration equipment, since absolute tightness is required. To connect a new compressor, it is necessary to use the brazing method (melting point above 450°C). Soft tin solder, used in electronics, will not work here, as it will not withstand freon pressure and vibration. You will need a gas torch and rods of copper-phosphorus solder.
Before soldering, insert the ends of the copper tubes into the compressor nozzles. The suction tube (thicker) and discharge tube (thinner) should fit into each other with a slight interference fit. Heat the joint with a torch until cherry red, then touch the solder. The molten metal should be drawn into the gap by capillary action, creating a monolithic joint. Do not overheat the tubes so as not to burn out the copper.
A filter-drier is a mandatory element of the system. It is installed on the liquid tube in front of the capillary and removes moisture and oil breakdown products. The old filter cannot be used - it must be replaced with a new one every time the circuit is depressurized. When soldering the filter, you need to act quickly and carefully so as not to overheat its body, otherwise the adsorbent inside will lose its properties.
| System element | Function | Connection material | Soldering temperature |
| :--- | :--- | :--- | :--- |
| Suction pipe | Freon gas supply | Copper | 600-700°C |
| Discharge pipe | Discharge of compressed freon | Copper/Steel | 600-700°C |
| Filter drier | Cleaning refrigerant from moisture | Copper/Steel | < 500°C (fast) |
| Capillary tube | Flow throttling | Copper | 600-700°C |
Evacuation and refrigerant charging
After soldering is completed, air remains in the system, which contains moisture and nitrogen. If you start the refrigerator with air inside, water vapor will freeze in the capillary tube, forming an ice plug, and nitrogen will increase the pressure in the system, which will lead to increased load on the compressor. Therefore, the vacuum step is critical. For this, a vacuum pump is used, connected to the service pipe through a manifold.
The process of pumping out air should last at least 30-40 minutes. The pressure gauge should show a deep vacuum (about -1 bar or lower). Only after creating a vacuum can you begin charging with refrigerant. For Biryusy freon R134a or R600ais most often used. The type of refrigerant is indicated on the nameplate on the back of the refrigerator, and the use of another gas is strictly prohibited due to differences in the properties of the oil and pressure.
⚠️ Attention: Refilling with freon R600a (isobutane) must be carried out with extreme caution, since this gas is explosive. Work should be carried out in a well-ventilated area, away from sources of open flame.
Refilling is carried out in the liquid phase (the container is turned upside down) with the compressor turned off in order to fill the calculated amount indicated on the label. After this, the unit starts up and refueling continues in the gas phase until the required pressure is reached, depending on the ambient temperature. It is better to control the process based on current consumption, which must correspond to the motor’s passport data.
First start-up and leak check
After filling, it is necessary to carry out a final check. Plug in the refrigerator and let it run for 15-20 minutes. At this time, listen carefully to the operation of the compressor: there should be no extraneous knocking, metallic clanging or excessive vibration. Check all solder joints with soapy water. If bubbles appear, it means that the seal is broken and the work needs to be redone.
Monitor the temperature of the evaporator inside the chamber and the condenser at the back. The evaporator should be evenly covered with frost (or be cold), and the condenser should be heated along the entire length of the coil. If only the upper part is heated, the capillary tube may be clogged or there is not enough freon in the system. Also check the current consumption with a clamp meter - it should not exceed the rating indicated on the compressor tag.
If all parameters are normal, you can install the protective casing and back panel. However, during the first day of operation, it is recommended to periodically check the temperature in the refrigerator and freezer compartments to ensure that the cooling is stable. Make sure that the compressor turns off when it reaches the set temperature, and does not work continuously.
Frequent installation errors
Even experienced craftsmen sometimes make mistakes that lead to all efforts are in vain. One of the most common is insufficient vacuum time. Many people think that 10 minutes is enough, but moisture from the oil and the walls of the tubes has time to evaporate only with prolonged pumping. This leads to the formation of acids in the system and corrosion of internal parts.
Another mistake is using the wrong oil. Compressors are already filled with oil at the factory, but during soldering some of it may burn out or mix with combustion products. If you change the type of refrigerant (which is not recommended) or the compressor, make sure the oil type is compatible. For R134a synthetic polyester oil (POE) is used, which is hygroscopic and quickly absorbs moisture from the air, so you need to open the system quickly.
The state of the start relay is also often ignored. Installing an old relay removed from a faulty compressor on a new motor is risky. The contacts inside could burn out, and the bimetallic plate could lose its properties. Always use a new relay that matches the power of the installed engine.
Is it possible to use a compressor from another refrigerator?
Yes, you can if the overall dimensions, type of refrigerant and power are the same. However, it is important to consider the type of oil and compatibility of the starting equipment. Compressors from foreign brands (Danfoss, Secop) are often more reliable and quieter than standard ones, but may require replacing the starting relay with an original one.
How long should the refrigerator cool down before turning it on after transportation?
If the compressor was transported in a horizontal position, oil could get into the circulation circuit. Before the first start, the refrigerator must stand upright for at least 4-6 hours (preferably a day) so that the oil flows back into the compressor crankcase.
Why does the compressor hum, but does not start?
The most likely reason is a malfunction of the starting relay or starting capacitor. It is also possible that the mechanical part of the compressor is wedged (the piston group is scuffed) or the starting winding is broken. In rare cases, the reason is low voltage in the network.
Is it necessary to change the filter drier when replacing the compressor?
Required. The filter drier is a disposable element. When the circuit is depressurized, it becomes saturated with moisture from the air and loses its ability to purify freon. Installing an old filter will lead to rapid breakdown of the new compressor due to ice plugs or acids.