Failure of a compressor is perhaps the most unpleasant scenario for the owner of refrigeration equipment, since this particular unit is the “heart” of the system. When the refrigerator stops cooling or starts working with an unnatural hum, the first thing that comes to mind is to replace the unit. However, simply buying the first motor you come across labeled “for a refrigerator” is a fatal mistake that can lead to failure of a new part or even a fire.
Selecting a compressor requires a careful analysis of the technical characteristics of the old unit, since modern cooling systems have become much more complex and energy efficient. You have to take into account not only the geometric dimensions and mounting holes, but also the type of refrigerant used, engine size, starting device and electrical power. Ignoring at least one of these parameters will make repair impossible or economically unfeasible.
In this article we will analyze in detail the algorithm for identifying a faulty unit, deciphering the markings and choosing a suitable replacement. You will learn why you can’t mix different types of freon and how to correctly calculate the required cooling capacity for your chamber.
Diagnostics of the fault and reading technical data
Before going to the store for spare parts, you need to make sure that the problem lies in the compressor, and not in the thermostat, start relay or freon leak. Often the symptoms of “not freezing” mask problems that are simpler and cheaper to fix. If the diagnostics have confirmed the death of the motor, your next task is to gain access to its nameplate (metal tag).
To do this, the refrigerator must be unplugged, moved away from the wall and the rear protective panel removed. At the bottom of the unit you will see a black barrel-shaped element - this is the compressor. A factory sticker is attached to its body or a marking is stamped on it containing all the necessary information. In some cases, especially after poor-quality repairs in the past, this tag may be lost or covered with paint, which significantly complicates the task.
You need to write down or photograph the following data: compressor model (for example Secop TL4.5G or Aspera NE6134GK), refrigerant type (R134a, R600a, R12), supply voltage, shaft speed and cooling capacity. It is also critically important to measure the geometric dimensions: height, width and depth of the body, as well as the distance between the mounting legs.
- 🔍 Model and manufacturer: the main identifier by which a complete analogue is searched in catalogues.
- ❄️ Refrigerant type: determines the chemical composition of the gas and the type of oil, confuse R600a and R134a.
- ⚡ Electrical parameters: power and starting current, important for selecting a starting relay.
- 📏 Dimensions: height, width, depth and diameter of tubes, affecting the possibility of installation in niche.
If the tag is missing, you will have to rely on visual signs and the model of the refrigerator itself. However, this approach is less accurate. In this case, you may need to consult with a professional technician, who, based on indirect signs, will be able to determine the type of unit required. Remember that installing an unsuitable motor threatens to destroy the entire refrigeration system.
⚠️ Attention: Before any manipulations with the compressor tubes, make sure that there is no pressure in the system. If you hear a hissing sound when you bite off the tube, it means that there is still freon in the system, which must be vented in a well-ventilated area, away from open fire.
Geometric dimensions and seating location
One of the most critical parameters when selecting is the physical size compressor. Refrigeration manufacturers design the bottom compartment with minimal clearances, so the new unit must fit into the existing space to the nearest millimeter. The main attention should be paid to the height of the housing, since it is this parameter that most often becomes the limiting factor.
Standard compressors are divided into several categories by height: low (about 100-110 mm), medium (about 120-130 mm) and high (more than 140 mm). If you install a compressor that is taller, it may hit the bottom of the refrigerator compartment or touch other structural elements, which will lead to vibration and destruction of the tubes. It is also important to check the diameter of the suction and discharge tubes - they must match the diameter of the copper tubes of your refrigerator for high-quality soldering.
The distance between the mounting holes (legs) must also match. In some cases, it is possible to use adapter plates or rubber dampers of a different configuration, but this requires additional installation skills. It is best to look for a model with an identical seat to avoid unnecessary modifications.
Below is a table of approximate sizes of popular types of compressors that are often found in household refrigerators:
| Size | Height (mm) | Width (mm) | Depth (mm) | Application |
|---|---|---|---|---|
| Low (L) | ~100-110 | ~110-120 | ~140-150 | Small refrigerators, R600a |
| Medium (M) | ~120-130 | ~120-130 | ~150-160 | Standard two-chamber |
| High (H) | ~140-150+ | ~130-140 | ~160-170 | Powerful units, old models |
| Inverter | ~110-130 | ~110-120 | ~140-150 | Modern models No Frost |
What what to do if the tubes do not match in diameter?
If the diameters of the tubes of the new compressor and your refrigerator differ slightly (for example, 5 mm and 6 mm), experienced craftsmen use adapter bushings or carefully flare the copper tube. However, this requires special tools and soldering skills. If there is a significant difference, it is better to look for another compressor model.
Refrigerant type and oil compatibility
The chemical composition of the refrigerant is perhaps the most important technical parameter that cannot be ignored. In modern refrigerators, isobutane (R600a) and tetrafluoroethane (R134a) are most often used. In older models produced before 2000, you can still find freon R12, which is now prohibited for production due to its harmful effects on the ozone layer.
Each type of freon requires the use of a strictly specific type of compressor oil. For R12 and R134a mineral oils have traditionally been used, but R134a also works great with synthetic oils like POE (polyolester). But for explosive R600a special oils are used, often with additives that reduce the flammability of the mixture. Mixing different types of oils or installing a compressor designed for one type of freon in a system with another will lead to rapid breakdown.
If you change a compressor from R12 to an analogue R134a (which is sometimes done in the absence of originals), it is necessary to completely flush the system and replace the capillary tube with a longer one, since these refrigerants have different thermodynamic properties. However, for R600a such a replacement is impossible - a strictly appropriate unit is required.
- 🧪 R12: outdated freon, requires mineral oil, prohibited in new systems.
- 💧 R134a: standard for most refrigerators from 2000-2010, requires POE or mineral oil.
- 🔥 R600a: modern environmentally friendly gas requires compressors with increased spark safety.
- ⚙️ Synthetics: POE oils are hygroscopic (absorb moisture), so evacuation of the system must be of very high quality.
Power and cooling capacity
Compressor power should not be “approximate”. It must match the heat flow of your refrigerator compartment. If you install a motor that is too weak, it will run non-stop trying to gain temperature, causing it to overheat and burn out after a short time. A unit that is too powerful will often turn on and off (clock), which is also harmful to the mechanics and starting equipment.
Cooling capacity is usually measured in watts (W) or kcal/hour at certain temperature conditions (for example, LBP - low temperature mode). The compressor markings often indicate the cylinder volume in cubic centimeters (cm³). The larger the volume, the higher the productivity. For example, a compressor with a volume of 8.7 cm³ will be more powerful than an analogue with a volume of 6.2 cm³.
When selecting an analogue, a power deviation within ±10-15% of the original is allowed, but only upward. That is, you can install the motor a little more powerful, but not weaker. However, for refrigerators with a system No Frost and two cooling circuits, this reserve should be minimal, since precise balancing of refrigerant flows is important there.
⚠️ Attention: Technical characteristics and compatibility of compressors can be updated by manufacturers. Always check the current cross codes and specifications in the official catalogs of manufacturers (Danfoss/Secop, Embraco, GMCC) before purchasing, as old directories may contain inaccuracies.
It is also worth considering the climate class of the refrigerator. If the equipment is intended to operate in a tropical climate, the compressor must have a safety margin and power higher than that of models for temperate climates.
Starting relay and electrical compatibility
The compressor cannot operate without a starting relay, which provides an impulse to start the engine and protects it from overloads. When replacing the motor, it is strongly recommended to change the start-protection relay (PZR), even if the old one looks good. New compressors are often supplied without a relay, since manufacturers expect the technician to select a suitable one or use an old one.
However, old relays may not fit the new motor due to differences in starting current. Relays are inductive, thermal and electronic. Modern compressors often require relays with more precise cut-off current settings. If you install a relay with a lower current, it will knock out when starting; if it is large, it will not protect the windings when jammed.
Pay attention to the type of connection: some relays are simply put on the compressor contacts, others require screw fastening or have a specific block shape. The orientation of the relay during installation is also important - there is always an arrow UP or TOPon the body, which should look straight up.
☑️ Check before soldering
Inverter compressors: replacement features
In recent years, inverter compressors have become increasingly popular, which smoothly regulate the shaft rotation speed, instead of constantly turning on and off. Replacing such a unit is a task of increased complexity. Firstly, inverter motors often have a unique housing and mount design, which makes finding a direct analogue difficult.
Secondly, and this is the main thing, the inverter compressor does not operate directly from a 220V network. It requires a special control unit (inverter), which converts the current and controls the rotation speed. When replacing a motor, it is often necessary to change the inverter unit itself, since the data exchange protocols between the “brains” of the refrigerator and the compressor may not match.
The cost of inverter units is much higher than usual, and their repair often requires specialized equipment for diagnosing the control board. If the inverter compressor in your refrigerator has burned out, sometimes it makes more economic sense to consider purchasing new equipment, especially if the refrigerator is more than 7-10 years old.
- 📉 Efficiency: inverters consume up to 40% less electricity.
- 🔇 Silence: no relay clicks and smooth start operation is almost silent.
- 💰 Price: replacement cost can be up to 70% of the price of a new refrigerator.
- 🔌 Complex: often require replacement of the control board and inverter unit.
FAQ: Frequently Asked Questions
Is it possible to replace the R12 compressor with R134a compressor?
Technically this is possible, but it requires a complete flushing of the system, replacement of the filter drier and often the capillary tube. The oils of these freons may be compatible, but the performance and pressures differ. It’s easier to look for an original analogue or a universal compressor that supports both types (marked R12/R134a).
Why does the new compressor heat up to 80-90 degrees?
For refrigeration compressors, the normal operating temperature of the housing can reach 70-90 degrees, especially in hot weather or when loading food for the first time. If the temperature is higher or a burning smell is heard, check the correct connection of the phases (for three-phase), the operation of the condenser fan and the absence of blockages in the system.
Is it necessary to vacuum the system before charging freon?
Yes, absolutely! Evacuation removes air and, critically, moisture from the system. The remaining moisture will freeze in the capillary tube, creating an ice plug, or react with the oil, forming an acid that will destroy the compressor from the inside.
Where can I find a cross-code (analog) for my compressor?
It is best to use the official catalog sites of compressor manufacturers (for example, Secop, Embraco, Danfoss). Enter the model of your old unit into the search engine, and the system will display a list of compatible modern analogues. There are also specialized tables of cross codes on the Internet.
How much does it cost to replace a compressor yourself?
The cost consists of the price of the compressor itself (from 3,000 to 10,000+ rubles), the cost of freon, filter-drier and consumables. However, please note that for a high-quality replacement you need a vacuum pump, a pressure gauge station and a burner, the rental or purchase of which may exceed the cost of the service of a specialist.