The situation when the refrigerator stops cooling or begins to emit an uncharacteristic hum, often leaves the owner with a choice: call a technician or try to solve the problem on his own. In most cases, the source of the malfunction becomes motor-compressor, which is the heart of the refrigeration system. It is he who is responsible for the circulation of the refrigerant, creating the necessary pressure in the circuit. Understanding how this unit works is critical for correct diagnosis.
However, it is worth immediately defining the boundaries of what is possible. It is almost impossible to disassemble the sealed housing compressor without damaging it without specialized equipment for welding and vacuuming. Therefore, by “disassembling the motor” in everyday conditions we mean it dismantling from the frame of the refrigerator, removing the protective casing and checking the starting protection equipment. This allows you to replace the relay, check the windings and eliminate simple mechanical faults.
Before taking active steps, you must be aware of the risks. There is oil and refrigerant inside the system, and the electrical contacts are at high voltage. An incorrect depressurization circuit will lead to the need for complex refilling with freon, which is extremely difficult to do at home. However, a competent approach to removing the unit is the first step to restoring the functionality of household appliances.
Preparation of the workplace and the necessary tools
High-quality preparation is the key to successful repairs. You will need not only physical access to the back wall of the refrigerator, but also a set of special tools. You should not try to unscrew the fasteners with a knife or screwdriver that is not suitable in size, as this will lead to the licking edges bolts. The main space should be well lit, and the floor should be covered with soft material to avoid damage to parts when dropped.
For work you will need the following tools:
- 🛠️ A set of screwdrivers (phillips and flat) for removing casings and terminals.
- 🔧 Open-end or socket wrenches (usually 8, 10, 12 mm) for compressor mounting nuts.
- ✂️ Side cutters or wire cutters for cutting copper tubes (if a complete replacement is planned).
- 🧤 Dielectric gloves for protection against residual voltage.
⚠️ Attention: Before starting any work, be sure to disconnect the refrigerator from the power supply! Even when turned off, a charge may remain in the capacitor circuit, which can cause an electric shock.
It is also important to prepare a container to collect oil that may leak from the compressor when it is tilted. If you plan to simply check the contacts, oil may not be needed, but when dismantling the unit, it will inevitably leak from the cut tubes. Having rags or paper towels on hand will greatly simplify cleaning.
Access to the compressor and removal of the protective casing
The first stage of disassembly is to gain access to the bottom of the refrigerator. In modern models compressor group located in a niche at the bottom of the rear wall. To access, you need to move the refrigerator away from the wall, providing room for maneuver. In some models, for example Indesit or Atlant, it may be necessary to remove the rear metal panel completely.
The protective casing (crankcase) is usually secured with latches or screws. Its main function is to protect electrical contacts and prevent oil from splashing in the event of a leak. Carefully bend the clamps or unscrew the fasteners. Do not use excessive force, as the plastic of old refrigerators becomes brittle and can crack from mechanical stress.
After removing the casing, you will have a view of the motor-compressor itself, the capacitor and the start relay. At this stage it is already possible to carry out visual diagnostics. Pay attention to the condition of the wires: there is no melted insulation, traces of burning or oxidation of the contacts. Often the cause of the malfunction lies in the burnt contacts relay, and not in the engine itself.
Disconnecting the electrical part and checking the relay
The electrical circuit for connecting the compressor is relatively simple, but requires care. A plastic box is attached to the end of the motor, which contains a starting and thermal relay. To remove them, you must carefully disconnect the power terminals. They are usually fixed with spring clips or screws.
The process of checking and removing the relay is as follows:
- 🔌 Remove the box from the compressor contact group, shaking it slightly.
- 👁️ Inspect the contacts for soot or oxidation, clean them when necessary.
- 🔨 Gently shake the relay: if a ringing is heard inside, it means the ceramic element or core is broken.
- 📏 Test the windings with a multimeter to identify a break or short circuit.
If you find that the relay is faulty, it can be replaced to a new one, without removing the compressor itself from the frame. However, if the problem is in the motor windings (turn-to-turn short circuit or break), a complete replacement of the unit will be required. In this case, you need to move on to the next stage - working with copper tubes.
How to check the windings with a multimeter?
Set the device in resistance measurement mode (Ohm). The normal resistance of the working winding is 10-30 Ohms, the starting winding is 20-50 Ohms. The resistance between the case and the contacts must be infinite (open). If the resistance is close to zero or shows a short circuit to the housing, the engine has burned out.
Removing the compressor: cutting the tubes and removing the fasteners
This is the most critical stage that requires caution. The compressor is usually secured to the refrigerator frame with four bolts with rubber shock absorbers. These shock absorbers dampen vibration, so it is important not to damage them when removing them. First you need to free the motor from the connection with the refrigeration circuit.
The copper tubes suitable for the compressor cannot simply be “unscrewed”, as they are often welded or soldered. To dismantle them, use a pipe cutter or nippers for soft metals. It is important to make a distance from the compressor housing of at least 10 cm in order to have a margin for subsequent soldering of the new unit. A sharp bend in the tubes is unacceptable, as this will block the channel cross-section channel cross section.
After disconnecting the tubes (or cutting them), unscrew the bolts securing the compressor feet to the frame. Be prepared for compressor oil to leak from the pipes. Place the prepared container. Also, part of the refrigerant will leave the system, so work should be carried out in a well-ventilated area, although freon in small quantities is not toxic, it displaces oxygen.
| Compressor type | Mode of fastening | Dismantling features | Weight (approximate) |
|---|---|---|---|
| Piston (classic) | 4 bolts on rubber washers | Requires cutting of tubes | 10-12 kg |
| Linear (inverter) | Specific clamps or bolts | Sensitive to shocks, requires caution | 8-10 kg |
| Sealed (small-sized) | 2 or 4 attachment points | Often comes complete with a capacitor | 6-8 kg |
⚠️ Attention: It is strictly forbidden to open the sealed welded housing of the compressor ("grinder" or hacksaw) at home! Inside there are freon vapors, which, when mixed with air, can form an explosive mixture, and when the insulation of the windings burns, phosgene, a chemical warfare agent, is released.
The nuances of working with different types of compressors
Disassembly and dismantling can vary significantly depending on the manufacturer and type of equipment. For example, in refrigerators Liebherr or Bosch Compressors with a horizontal shaft arrangement are often used, which are mounted in a special suspension basket. Their removal requires careful disengagement from the dampers.
In two-compressor models (where one motor is for the refrigerator, the other for the freezer), it is important not to confuse the units. They can have different power and performance. The marking is usually applied to a nameplate located on the side of the case. When replacing, it is necessary to select an analogue with identical characteristics, otherwise the system will not work correctly.
☑️ Checklist before installing a new motor
Inverter compressors deserve special attention. They work on a different principle and do not have a classic starting relay. Their diagnosis is carried out by measuring the resistance of the windings and checking the control board. It is almost impossible to disassemble such a “motor” without damaging the electronics, so if they malfunction, the complete assembly is most often replaced.
Frequent errors during disassembly and precautions
One of the most common mistakes is trying to bend copper tubes by hand without a special tool. Copper is a soft metal, and when strongly bent, the tube walls collapse, cutting off the freon flow. It is extremely difficult to restore the patency of such a tube; overcooking is often required.
Also, beginners often forget about transport plugs. If you are removing an old compressor for disposal and installing a new one, the fittings on the new unit are closed with rubber or plastic plugs. They should only be removed at the last moment before soldering to prevent moisture and dust from getting inside. Moisture in the system is a guarantee of the formation of ice plugs and failure of the capillary tube.
Another critical error is turning on the compressor “in air” (without connecting to the system) for more than 1-2 minutes. Such motors are designed for cooling by a flow of passing gas. Long-term idle operation will lead to overheating and thermal breakdown of the winding insulation.
Is it possible to disassemble the compressor in order to rewind it yourself?
Theoretically, yes, the housing can be cut. However, in practice, rewinding the stator at home is impossible due to the need to use a special heat-resistant varnish, precise winding and subsequent vacuum assembly. The cost of such work will exceed the price of a new compressor, and the reliability will be questionable.
Why does the refrigerator not freeze after replacing the compressor?
The most likely reason is the presence of an air lock or moisture in the system, or an insufficient amount of freon. The problem may also be a clogged capillary tube (often forgetting to remove the shipping plug from a new compressor before soldering) or a malfunction of the thermostat.
What kind of oil should be poured into the compressor when replacing?
The type of oil depends on the type of refrigerant. For R134a freon, synthetic polyester oil (POE) is used, for R600a - mineral or alkylbenzene. It is strictly forbidden to mix different types of oils, as this will lead to the formation of sediment and blockage of the system.
A knocking sound is heard inside the compressor during operation - is this normal?
No, this is not normal. A knocking sound indicates mechanical wear: the shaft bearings are broken, the piston rings or valves are damaged. Such a compressor must be replaced, since its efficiency has dropped to zero, and the risk of a piston group wedge is very high.