Failure compressor is one of the most serious malfunctions that can occur face the owner of refrigeration equipment. It is this unit that is the “heart” of the system, circulating the refrigerant and creating the necessary pressure to cool the chambers. If you hear the motor humming but not starting, or it is running continuously without reaching the set temperatures, it most likely needs to be replaced. Independent installation of a new unit is a complex technical process that requires not only mechanical skills, but also specialized equipment for working with gases.
Before you begin to dismantle the old and install a new engine, you must clearly understand the risks. The work involves high pressure, electric current and the use of flammable gases. Improper sealing of connections will lead to leakage freon and repeated failure of the equipment, and errors in soldering can cause a fire. In this article we will analyze in detail each stage of the process, from choosing a compatible model to the final filling of the system with refrigerant.
It is worth noting that modern inverter models require a special approach and often cannot be replaced at home without factory software. However, for classic refrigerators with piston compressors, the procedure is standardized. It is critically important to select a compressor with identical cooling capacity and type of refrigerant, otherwise the system will not work correctly or will quickly fail. Be prepared for the process to take several hours and require full concentration.
Diagnostics of the malfunction and preparation of tools
The first step is to accurately determine the cause of the breakdown. The absence of cold does not always mean the death of the engine; Sometimes the problem lies in the start relay or thermostat. If the compressor hums but does not start, or it turns on for a few seconds and immediately turns off with a click, this is a sure sign of mechanical jamming or broken windings. It is also worth checking the integrity of the electrical circuit and the presence of voltage at the terminals.
To successfully carry out the work, you will need a specific set of tools, which is not always in the arsenal of a home craftsman. The main elements are pipe cuttera rolling tool, a burner (gas or oxygen) and a pressure gauge station. Without a vacuum pump and scales for accurate freon charging, high-quality installation is impossible. The use of artisanal methods often leads to moisture entering the system, which causes corrosion and the formation of ice plugs.
Pay special attention to workplace safety. The room should be well ventilated, since the combustion of old oil and possible gas leakage may release harmful substances. Prepare a fire extinguisher in advance and make sure there are no flammable objects nearby. You will also need technical fluids for flushing the system and a new filter-drier, which must be changed every time the circuit is opened.
⚠️ Attention: Before starting any work on the electrical part of the refrigerator, be sure to disconnect the device from the mains. Residual voltage in capacitors can be dangerous, so let the equipment stand unplugged for at least 15-20 minutes.
Removing the old compressor and preparing the system
The process of removing the faulty unit begins with access to the technical area, which is usually located in the lower rear part of the refrigerator. Remove the protective cover and visually inspect the condition of the tubes and wires. Carefully disconnect the electrical terminals, having previously photographed the connection diagram so that when installing a new motor you do not mix up the contacts. Often the wires become stuck to the terminals and must be removed carefully so as not to damage the insulation.
The next step is to remove the old refrigerant. To do this, you need to cut through the filling tube, which usually has a characteristic bend. If there is pressure left in the system, the gas will come out with a hissing sound. After releasing the pressure, it is necessary to unsolder the suction and discharge tubes from the compressor housing. Use a pipe cutter or hacksaw to make cuts, but do not pinch the copper tubes so as not to disrupt their permeability.
After disconnecting the tubes, the compressor is usually attached to the refrigerator frame with four bolts or special shock-absorbing bushings. Unscrew the fasteners and remove the old motor. At the same stage, it is recommended to inspect the condenser (radiator on the rear wall) for mechanical damage or severe corrosion. If the radiator is damaged, its repair or replacement is required before installing a new compressor.
☑️ Dismantling checklist
Selecting a compatible compressor model
Selecting a new unit is not just about buying a part with a similar appearance. The nameplate (metal plate) of the old compressor contains all the necessary information: model, type of refrigerant (R134a, R600a, R12), power in BTU or watts, as well as oil type. Cooling capacity the new motor should be equal to or slightly exceed (up to 10%) the power of the old one. Installing a compressor that is too powerful will lead to frequent switching on and off, and a weak one will result in insufficient cooling.
Pay special attention to the type of refrigerant. If your refrigerator operated on isobutane (R600a), which is explosive, you should absolutely not use a compressor designed for freon, and vice versa. There are also different types of oils: mineral, semi-synthetic and synthetic (POE). Mixing different types of oils can lead to the formation of an acidic environment and system failure.
The modern market offers original spare parts and universal analogues. The originals guarantee full compliance with the dimensions and characteristics, but they are more expensive. Universal models may require modification of the mounting holes or the use of adapters. When purchasing, be sure to check the presence of a filling fitting, since some budget models are supplied without it, which will complicate the process of evacuation and filling.
Is it possible to install a compressor of greater power?
Theoretically, installing a more powerful compressor is possible, but this requires recalculation of the entire refrigeration system. Increasing the power will lead to the fact that the evaporator will not have time to give off cold, and the condenser will not have time to dissipate heat. This will cause an increase in pressure in the system, overheating the motor and reducing its service life. In addition, the thermostat may incorrectly control operating cycles, which will lead to defrosting of products or, conversely, their refreezing.
Soldering connections and installing a filter-drier
Installation of a new compressor begins with the preparation of copper tubes. The ends of the pipes that will connect to the motor pipes must be cleaned of oxides and degreased. If the diameters of the tubes do not match, special adapters are used. The soldering process requires the use of solder with a melting point above 600°C and flux. It is important to heat the connection evenly so that the solder flows inside the gap under the action of the capillary effect, and does not just flow from the outside.
A mandatory element for any depressurization of the system is replacement filter-drier. This component removes moisture and oil breakdown products from the circuit. The old filter is dismantled and a new one is installed in its place. The direction of refrigerant flow is indicated by an arrow on the filter housing; setting in the opposite direction will block gas circulation. Soldering of the filter should be done quickly so as not to overheat its body, since there is zeolite inside, which loses its properties when heated strongly.
When soldering, follow safety precautions: the burner flame should not be too long so as not to melt the adjacent plastic elements of the refrigerator. Use heat sink clips or damp cloths to protect nearby areas. After completing the soldering of all connections (discharge, suction, filter), it is necessary to allow the system to cool naturally. Do not try to speed up the process with water or compressed air, as sudden temperature changes can cause cracks in the seams.
Evacuation and leak testing
After assembling the mechanical part of the system, the most critical stage begins - evacuation. The presence of air and moisture in the circuit is unacceptable. The air creates excess pressure, increasing the load on the compressor, and moisture at low temperatures turns into ice, clogging the capillary. To remove air, a vacuum pump is used, connected to the service connection through a pressure gauge station.
The vacuuming process should last at least 30-40 minutes. The pressure gauge should show a value close to -1 bar (or 30 inHg). After reaching a vacuum, the pump is shut off and the system is left under vacuum for another 15-20 minutes to check the tightness. If the pressure gauge needle begins to creep up, it means that there is a leak in the system, and all connections must be rechecked using a soap solution or a leak detector.
The table below shows the main parameters that you should focus on when working with different types of refrigerants:
| Parameter | R134a | R600a (Isobutane) | R12 (Obsolete) |
|---|---|---|---|
| Oil type | Synthetic (POE) | Mineral / Alkylbenzene | Mineral |
| Vacuum pressure | up to -1 bar | up to -1 bar | up to -1 bar |
| Vacuum time | 30-40 min | 40-50 min (requires care) | 30 min |
| Danger | Safe | Explosive | Toxic |
⚠️ Attention: Never turn on the compressor if a vacuum has been created in the system, but the refrigerant has not yet been charged. Working “dry” or in a vacuum without load can lead to breakdown of the winding insulation and combustion of the motor in a matter of seconds.
Filling with refrigerant and final adjustment
Filling the system with refrigerant is carried out strictly according to the weight indicated on the nameplate of the refrigerator or in the technical documentation. Using a weight cylinder is the only correct method. Filling “by eye” or by pressure in static conditions (when the compressor is turned off) is unacceptable, since the amount of phase state of the gas depends on the ambient temperature. Open the valve on the cylinder and supply gas to the system in small portions, monitoring the scales.
After the initial filling in static conditions (without turning on the motor), it is necessary to start the compressor and continue supplying refrigerant into the operating system through the suction tube. At this point, monitor the pressure on the low pressure gauge and the temperature of the suction tube. It should be slightly cool, but not covered with frost right up to the compressor. The appearance of frost on the motor body indicates that the system is overfilled with liquid freon, which threatens water hammer.
The final step is to seal the filling fitting. After disconnecting the station hose, the copper pipe is cut and sealed “tightly”. The soldering area is checked with a soap solution for bubbles. Only after making sure that it is completely sealed can you install the protective casing and connect the refrigerator to the network for test operation. The full cooling cycle and stabilization of temperatures can take up to 24 hours.
How long does it take to completely replace a compressor?
B On average, a qualified technician needs from 2 to 4 hours to completely replace a compressor, taking into account the time for soldering, vacuuming and initial charging. However, if flushing the system is required due to engine combustion, the time may increase to 6-8 hours. Replacing it yourself without experience can take a whole day or more.
Is it necessary to flush the system when replacing a compressor?
Yes, if the old compressor burned out or jammed, oil combustion products and metal shavings got into the system. Flushing with a special solvent or nitrogen under pressure is mandatory. If the compressor simply stops pumping without visible signs of burning, flushing may not be necessary, but replacing the filter-drier is required in any case.
Why does the refrigerator freeze worse after replacing the compressor?
There may be several reasons: the compressor power was incorrectly selected, there is moisture or air left in the system (poor vacuuming), clogged capillary or filter, or the dosage of refrigerant is incorrectly selected. It is also worth checking the tightness of the door seals, which may have worn out.