Many owners of household appliances are faced with the need to understand the internal structure of the unit when the refrigerator stops freezing or starts working too loudly. Looking behind the back wall, you can see a complex system of copper tubes leading to a black barrel - the compressor. It is these elements that are the circulatory system of your refrigerator, ensuring the circulation of the refrigerant.
Understanding this What are the tubes on the compressor for?is important not only for general development, but also for the correct diagnosis of malfunctions. Understanding the operating principle of the suction and discharge lines will help you distinguish a normal phenomenon from a critical breakdown. In this article we will look in detail at the purpose of each compressor output and their role in the refrigeration cycle.
The principle of operation of the compressor in the cooling system
The compressor is the heart of the refrigeration unit, creating the necessary pressure for the movement of freon. Its job is to compress the refrigerant gas coming from the evaporator and push it out at high pressure into the condenser. This process is accompanied by a significant increase in gas temperature, which is a fundamental law of physics that is used in the heat removal cycle.
To ensure this process, the design provides for the presence of inlet and outlet openings. Suction tube designed to receive low-pressure cold steam from an evaporator located inside the chambers. At the same time, through the discharge line, the compressed gas is directed to the heat exchanger, where it releases the accumulated heat to the environment. Without a clear separation of these flows, the operation of the refrigerator would be impossible.
It is important to understand that the movement of freon occurs in a closed circuit, and the compressor only gives it an impulse. If the tightness of the connections is broken or a blockage occurs, the pressure balance in the system is thrown off. That is why technical condition pipe connections directly affect the refrigerator’s ability to maintain the set temperature.
Main types of pipes and their purpose
On the body of a standard household compressor there are usually three main pipes, each of which performs a strictly defined function. They must not be confused, as this will lead to damage to the unit. Let's look at the purpose of each of them in more detail.
The first and most noticeable is discharge tube. It has the smallest diameter and is often connected to the condenser (the grill at the back of the refrigerator) through a thin capillary tube or filter drier. Hot freon comes out through it under high pressure. It is this section of the system that is most susceptible to vibration, so it is important to monitor the integrity of its fastenings.
The second key line is suction tube. It has a larger diameter and connects the compressor to the evaporator. Through it, gaseous refrigerant that has already spent its life is sucked into the compressor. The third, often shorter pipe, can be used to fill the system or vacuum during repairs, but in some models it is missing or plugged.
Suction line function
The suction tube plays a critical role in the efficiency of the refrigerator. Through this channel, the compressor receives gaseous freon low pressure. Under ideal conditions, only gas should be present here. If liquid refrigerant gets into this line, it can lead to water hammer, which can destroy the compressor valves and damage the motor.
The diameter of this tube is always larger than the diameter of the discharge tube. This is done in order to reduce resistance to gas flow and ensure unhindered movement of refrigerant to the pump. Often in this area you can see a heat insulator - a black or gray foam tube. It is necessary to prevent the formation of condensation on the metal surface and reduce heat loss.
In some modern models with the system No Frost an additional defrost line can be connected to this tube. This allows the heat from the exhaust gas to be used to evaporate moisture in the drainage system. However, in classical schemes, it performs only one function - returning the refrigerant for a second compression cycle.
⚠️ Attention: If the suction tube becomes covered with frost or ice while the refrigerator is operating, this is a signal of a malfunction. Most often, this indicates a clogged capillary, a freon leak, or a thermostat malfunction. Operation in this mode is dangerous for the compressor.
The role of the discharge pipe
Through the discharge pipe, the refrigerant compressed by the compressor enters the condenser. Here the gas is under high pressure and has a high temperature. It is this section of the system that is responsible for releasing the heat collected inside the refrigeration chambers into the room. The efficiency of heat removal directly depends on the throughput of this line.
Due to high pressure and temperature, increased requirements for tightness are imposed on this section. The connection of the discharge tube to the condenser is often made through filter drier. This element is necessary to remove moisture from the system that may have entered during assembly or during operation. Moisture in the system is fatal to the compressor and capillary.
It is important to note that the discharge tube is always hot. If it remains cold when the compressor is running, this indicates that the system is not working: either there is no freon, or the compressor does not create compression (for example, due to breakdown of the valves). Checking the temperature of this area is the first step in diagnosis.
☑️ Diagnosis of compressor operation
Technical characteristics and materials
For the manufacture of tubes in refrigeration technology, copper is mainly used. This material was not chosen by chance: it has excellent thermal conductivity, ductility and corrosion resistance. Copper tubes are easily soldered, which simplifies repair and maintenance of the system. However, copper is susceptible to oxidation, so it is important to keep the connections clean.
Some budget models or in certain areas of the system may use copper-plated steel tubing or aluminum alloys. Steel is stronger, but less amenable to soldering and requires the use of special solders. Aluminum is lightweight, but very sensitive to mechanical damage and electrochemical corrosion when in contact with other metals.
Below is a table showing the main differences between compressor lines:
| Parameter | Suction tube | Discharge tube | Process tube |
|---|---|---|---|
| Freon pressure | Low | High | Depends on stage |
| Temperature | Low (often with condensation) | High (hot) | Variable |
| Diameter | Larger | Smaller | Medium |
| Flow direction | To compressor | From compressor | For refueling |
Problems and malfunctions of tubes
The most common problem associated with compressor tubes is a leak. Microcracks can occur in soldering or bending areas due to the constant vibration of a running motor. A freon leak causes the refrigerator to stop cooling, and the compressor works nonstop, trying to compensate for the loss of pressure.
Another common problem is clogging. Oxidation products, dust or moisture may enter the system. Moisture, freezing in a narrow place in a capillary or filter, forms an ice plug that blocks circulation. Copper oxides or oil combustion products can clog the filter drier, which will lead to an increase in discharge pressure and overload of the compressor.
Mechanical damage also occurs frequently, especially with careless transportation or attempts at self-repair. A pinched tube disrupts the patency of the system. If you notice that the tube is deformed, do not try to straighten it by force - the thin walls may burst.
Why can't you just weld the tube?
When soldering copper refrigerator tubes, it is critical to use nitrogen. If you solder without purging with nitrogen, scale (copper oxide) will form inside, which after a short time will clog the capillary filter, and the refrigerator will stop working again.
⚠️ Attention: Never try to repair a cracked tube using cold welding or sealants. High pressure and an aggressive refrigerant environment will quickly destroy such patches. Professional soldering is required with replacement of the damaged area.
Tips for diagnostics and maintenance
For independent initial diagnosis of the condition of the tubes and compressor, no complex equipment is required. First of all, pay attention to the appearance. The tubes must not have any traces of oil. If you see oily spots on copper connections, this is a sure sign of a freon leak, since oil circulates along with gas in the system.
Listen to the sounds. Normal operation of the system is accompanied by a quiet hum and periodic gurgling in the tubes (freon current). If you hear a whistle, hissing or sharp clicks in the area of the pipes, this may indicate an air leak or a breakdown of the valves. Vibration of the tubes should be minimal; if they rattle heavily against the body, check the rubber shock absorbers.
When servicing, it is important to keep the back wall of the refrigerator clean. Dust accumulating on the condenser and in the area of the compressor tubes impairs heat transfer. This forces the compressor to work longer and harder, which increases the temperature of the discharge tube and reduces the life of the unit. Regular dry cleaning of this area will extend the life of your refrigerator.
Frequently asked questions (FAQ)
Why suction Is the tube covered with frost?
Icing of the suction tube usually indicates that liquid freon is entering the compressor, not gas. This may be due to a faulty thermostat that does not turn off the compressor in time, or due to a blockage in the system causing pressure surges. Also, the cause may be a freon leak.
Is it possible to replace the compressor tube yourself?
Theoretically, this is possible if you have the skills to solder copper pipes and the necessary equipment (torch, solder, vacuum pump, pressure gauge station). However, without experience, there is a high risk of making a mistake that will lead to damage to the compressor or a fire hazard. It is better to entrust this work to professionals.
What temperature should the discharge tube be?
In normal operation, the discharge tube should be hot, the temperature can reach 60-80 degrees Celsius and higher, depending on the model of the refrigerator and environmental conditions. It should not be red-hot, but confidently hot to the touch.
Why do you need a filter on the compressor tube?
The filter drier installed at the outlet of the compressor (on the discharge line) performs two functions: it retains mechanical impurities (dust, chips, wear products) and absorbs moisture entering the system. This protects the capillary tube from clogging and prevents corrosion of internal parts.