The situation when in one refrigerator the motor-compressor fails, and in another, for example, written off or faulty for another reason, the working motor is intact, often confronts the owner with a choice: buy a new part or try to revive the equipment by rearranging it. Repositioning the compressor is a complex technical process that requires not only mechanical skills, but also specific equipment, such as vacuum pump and torch for soldering copper tubes. A simple bolt-to-bolt replacement will not work here, since the system is sealed and under pressure.
Before proceeding with dismantling, you need to make sure that coolant parameters and the type of oil in both units are compatible. Using an unsuitable compressor can lead to rapid failure of the entire cooling system or even an explosive situation if incompatible oils are mixed. In this article we will analyze all the stages of engine transfer, technical nuances and risks that you will face.
It is worth noting right away that this operation requires high qualifications. The tightness of the system is a critical parameter; any microcrack in the seam will lead to a freon leak and repeated repairs. If you do not have experience working with copper pipes and refrigeration equipment, it is better to entrust this work to professionals, since the cost of an error can exceed the cost of a new refrigerator.
Diagnostics and checking the compatibility of equipment
The first step is a thorough check of the donor compressor. You can’t just remove the motor from a refrigerator that’s been lying around for years and hope for a miracle. It is necessary to ring the windings with a multimeter and check the resistance between the contacts and the housing. If the resistance approaches zero or infinity, the part is unusable. It is also important to visually inspect the pipes: if they are pinched or have signs of corrosion, they will have to be replaced.
The second important aspect is the compatibility of characteristics. The compressor power must correspond to the volume of the evaporator and condenser of the receiving refrigerator. Installing a unit that is too powerful will lead to frequent switching on and off (clocking), which will quickly kill the start relay. A motor that is too weak will not be able to gain the required pressure, and the products will begin to deteriorate.
- 🔍 Check the markings on the nameplate of the donor motor and compare it with the required parameters of the recipient.
- ⚡ Measure the resistance of the windings: it should be within the passport values for the specific model.
- 🛢️ Make sure that the type of refrigerant (R134a, R600a) matches, since the oils for them have different chemical bases.
⚠️ Attention: Never mix oils of different types! Mineral oil is incompatible with synthetic oil (POE), their interaction leads to the formation of acids and blockage of the capillary system.
Necessary tools and preparation of the workplace
To successfully move the compressor, a regular set of household tools will not be enough. You will need specialized equipment to work with refrigeration systems. The main tool will be a gas torch with solder (copper-phosphorus or silver) for soldering copper tubes. The use of tin in high-pressure refrigerator systems is not recommended due to low bond strength.
A vacuum pump and gauge station are also critical. After installing the compressor, there will be air and moisture in the system that must be removed. Evacuation is a process that cannot be ignored, otherwise the moisture will react with the oil and refrigerant, forming an acid that will corrode the motor windings from the inside.
☑️ Tools for replacing the compressor
Don't forget to prepare a container to collect old oil and refrigerant. Freon cannot simply be released into the atmosphere; it is harmful to the environment and is often prohibited by law. The workplace must be well ventilated, since during soldering and possible gas leakage harmful compounds can form.
Removing the old compressor and preparing for installation
The process begins with completely disconnecting the refrigerator from the power supply. Then you need to gain access to the rear of the unit. Remove the protective cover, if equipped, and locate the motor-compressor. Before cutting the pipes, it is recommended to bleed the remaining refrigerant through the puncture, taking precautions.
Using a pipe cutter, carefully cut the suction and discharge pipes. Do not use a hacksaw as it will leave chips that will get inside the system. Copper or steel shavings are death for the compressor; they will clog the filter drier and can jam the piston group.
After removing the old motor, it is necessary to prepare a new (donor) unit. If it has been sitting for a long time, its pipes may be oxidized. They need to be cleaned out. It is also worth replacing the filter drier on the receiving refrigerator, since the old one could be saturated with moisture and lose its properties.
⚠️ Attention: When dismantling, avoid sudden movements and impacts on the condenser and evaporator tubes. The aluminum tubes of modern refrigerators are damaged, and their repair requires argon welding.
Why can’t you open the system without nitrogen?
If you open the system and leave it open for a long time, moisture from the air will get inside. Moisture is the main enemy of the freon system. It freezes in the capillary tube, creating an ice plug, and reacts with the oil to form an acid. Therefore, all soldering work must be carried out quickly, and the system must be constantly under a slight excess nitrogen pressure if a pause in operation is required.
The technology of soldering and installing a new motor
Installing the compressor in place requires reliable fastening. Use standard shock absorbers or rubber gaskets to prevent vibration from being transmitted to the refrigerator body and creating noise. Connect the tubes: suction (usually larger diameter) and discharge (smaller diameter). Make sure that the tubes do not touch each other and the body, otherwise vibration will wear them out.
Soldering copper connections is the most critical stage. The pipe is heated evenly around the circumference, after which solder is introduced into the flame zone. It should flow into the gap under the influence of the drip effect. The quality of the seam is checked visually: it must be smooth, without cavities and sagging.
After soldering all connections, nitrogen pressure testing is performed. This is a leak test. The system is pumped with nitrogen under pressure (usually 10-15 atmospheres for R134a and higher for R600a) and left for several hours. If the pressure gauge shows a drop in pressure, then there is a leak somewhere that needs to be found and sealed.
| Parameter | R134a | R600a (Isobutane) | Old R12 |
|---|---|---|---|
| Oil type | Synthetic (POE) | Mineral | Mineral |
| Discharge pressure | High | Low | Average |
| Danger | Safe | Explosive | Toxic |
| Difficulty of soldering | Medium | High (ventilation needed) | Low |
Evacuation and charging with refrigerant
After successful pressure testing, the evacuation stage begins. A vacuum pump is connected to the system. The process should last at least 30-40 minutes, and for large-volume systems - up to an hour. The goal is to remove all air and evaporate moisture contained in the system. The residual pressure should be close to zero.
Filling with refrigerant is carried out only after creating a vacuum and with the compressor running (if the design allows) or statically, strictly by weight. The amount of freon is indicated on the refrigerator nameplate (for example, 130 grams). Refilling “by eye” or by pressure in household refrigerators often leads to errors, since the pressure depends on the ambient temperature.
Use electronic scales for accurate dosing. Refilling is dangerous because liquid freon can get into the compressor, causing water hammer, and also increase the load on the engine. Under-refueling will lead to insufficient cooling and overheating of the engine.
⚠️ Attention: R600a (isobutane) is explosive! All work with this gas, including soldering and refilling, should be carried out in a well-ventilated area away from open flames. A spark from a relay or poor contact can cause ignition.
Starting and testing the system
After refueling, you need to start the refrigerator and check its operation. In the first minutes, listen to the sound of the compressor: it should be smooth, without knocking or vibration. Check the heating of the motor housing - it should not heat up to temperatures at which it is impossible to hold your hand.
Evaluate the operation of the refrigeration and freezer compartments. Cooling should begin within 30-40 minutes. If after an hour of operation (the evaporator) is not evenly covered with frost or the compressor is running without shutting down, perhaps the amount of refrigerant was selected incorrectly or there is an air lock in the system.
The final stage is installing a protective casing and monitoring the equipment during the day. Make sure that the refrigerator comes into operation and the on/off cycles are normal. If all parameters are in order, the rearrangement can be considered successful.
Frequently asked questions (FAQ)
Is it possible to install a compressor of higher power on the refrigerator?
Theoretically, it is possible if the supply voltages are the same, but this is not recommended. A more powerful motor will operate in a short cycle (on and off frequently), which will quickly wear out the start relay and the compressor itself. In addition, heat exchangers may not have time to release heat.
Is it necessary to change the filter drier when replacing a compressor?
Yes, definitely. The filter drier is a disposable element. When the system is opened, it instantly absorbs moisture from the air and loses its ability to protect the system. Installing an old filter will negate all evacuation efforts.
Why does the refrigerator hum after replacing the compressor?
The hum can occur due to improper fastening (vibration is transmitted to the housing), the tubes touching each other or the housing, or because the new compressor itself is noisier. Also, the reason may be airiness of the system or improper filling.
How much does it cost to refill with freon after replacement?
The cost depends on the type of refrigerant and volume. Typically, craftsmen charge a fixed price for the job plus the cost of gas. At home, without scales and a station, refueling “by eye” is extremely risky and can lead to damage to the product.