Detection of an ice crust on the pipelines of a refrigeration unit is the first alarm signal that should not be ignore. Many owners of household appliances mistakenly believe that a little frost on the back wall or tubes is the norm, but systematic freezing indicates a violation of the operating cycle refrigerant. If you ignore this symptom, you can lead the compressor to expensive repairs or complete replacement.
The refrigeration system is a closed circuit, where freon circulates under a strictly defined pressure. Any deviation from the standard parameters is immediately reflected in the temperature regime of the evaporator. Most often, the problem lies in depressurization, moisture ingress, or a mechanical obstruction to the gas.
In this article, we will analyze in detail the physical processes that lead to the formation of ice in different parts of the circuit, and provide a step-by-step diagnostic algorithm. Understanding the principles of operation of the refrigeration circuit will help you avoid fatal mistakes when trying to troubleshoot the problem yourself.
Principal diagram of the operation of the refrigeration circuit
To understand the nature of freezing, it is necessary to briefly consider the path of the refrigerant. The compressor compresses the freon gas, increasing its temperature and pressure, and then sends it to the condenser. There the gas cools and turns into liquid, releasing heat to the environment.
Next, the liquid refrigerant passes through capillary tube (a throttling device), where its pressure drops sharply. It is at this moment that the substance sharply cools, and it enters the evaporator, where it boils, actively absorbing heat from the refrigerator chambers.
Why is the capillary tube critical?
The capillary tube has a very small internal diameter (less than 1 mm). This is where the main hydraulic resistance of the system is created. Any microscopic particle of dirt or drop of water that has turned into an ice plug can completely block circulation.
It is important to note that the boiling point of freon directly depends on the pressure in the system. If the pressure drops below the design pressure, the boiling point decreases, resulting in excessive cooling and freezing of areas that should be warm or have only light condensation.
An imbalance between the liquid and gaseous phases of the refrigerant is a key factor in the formation of ice. In normal operation evaporator covered with frost evenly, and the return pipe (suction) should be slightly cool, but not icy.
Main reasons for freezing of the return pipe
The return (suction) pipe connects outlet from the evaporator with inlet to the compressor. In a working refrigerator, freon gas moves through it. If you observe an ice coat or “sweating” of this tube right up to the compressor itself, this is a sign that liquid refrigerant is entering the compressor.
Liquid freon is not compressed, but hydraulically hits the valves and piston group. This phenomenon, known as hydraulic hammer, can lead to the destruction of the compressor valve plate in a matter of hours of operation. The main reasons for this condition:
- ❄️ Malfunction of the thermostat: The sensor does not turn off the compressor in time, and the evaporator is overcooled, not having time to completely convert the freon into gas.
- ❄️ Excessive filling: If during the previous repair the system they pumped in too much freon, the excess amount of substance does not have time to evaporate.
- ❄️ Clogged evaporator: Heat transfer disturbance due to a thick layer of ice inside the chamber (often in No Frost systems when defrosting is faulty).
It is also worth considering the condition of the thermal insulation. If there is no ice on the tube, but it constantly “cries” (condensation), this may indicate damage to the insulation or the temperature inside the chamber is too low.
In some models of refrigerators Indesit or Atlant there is a design feature when the return line passes through the freezer. In this case, local freezing of the area inside the chamber is acceptable, but the exit of the pipe outside the cooling zone must be dry.
Freezing of the capillary tube and filter drier
The capillary tube is a thin copper coil connecting the condenser and evaporator. At the point where it enters the evaporator, the formation of an ice “finger” or ball is often observed. This is a classic symptom hydraulic resistance.
Most often the problem lies in the filter drier, which is located in front of the capillary. Its task is to retain moisture and microparticles. If the filter is saturated with moisture or clogged with oil oxidation products, the permeability of the system decreases.
Moisture in the system is the main enemy. At low temperatures, water freezes in the capillary area, forming an ice plug. The circulation stops, the suction pressure drops, and the tube freezes even more. After turning off the refrigerator, the plug melts, the system briefly works normally, but then the cycle repeats.
You can diagnose a blockage by touch: if the filter drier is colder than the environment or is covered with frost, and the evaporator does not cool, there is a flow blockage.
To eliminate this problem, you need to evacuate the system, replace the filter drier and refill a new one portion freon. It is impossible to carry out this procedure independently without a pressure gauge station and a vacuum pump.
The influence of freon leakage on ice formation
Paradoxically, a refrigerant leak can also lead to local freezing, although more often it causes a complete absence of cold. With a small leak, the pressure in the system drops, which reduces the boiling point of freon in the initial part of the evaporator.
As a result, an ice lump forms at the point where freon exits the capillary tube, while the rest of the evaporator remains warm. The compressor works continuously, trying to gain temperature, but due to a lack of substance it cannot do this.
Leakage symptoms are often accompanied by:
- 🔥 Hot condenser: The rear grille heats up unevenly or only at the beginning.
- 🔥 Lack of cold: The products in the chamber begin to deteriorate, despite the operation of the motor.
- 🔥 Corrosion: Visible traces of rust or oil stains on the tubes (oil leaks out along with the gas).
It is important to understand that you cannot simply “top up” freon in the event of a leak. It is necessary to find the location of the damage, solder it, replace the filter and recharge the system according to the scale.
If you ignore the leak, the compressor will work for wear, trying to compensate for the lack of refrigerant, which will lead to overheating and inter-turn short circuit of the windings.
Malfunctions of the thermostat and electronics
Modern refrigerators are controlled by electronic modules, while in older models a mechanical module is responsible for this. thermostat. If this element fails and “sticks” in the “On” position, the compressor does not receive a command to stop.
As a result, the evaporator is supercooled, and all the incoming freon does not have time to evaporate. Liquid drops of freon return to the compressor through the return pipe, causing it to freeze and the risk of water hammer.
In refrigerators with a system No Frost The cause may be a malfunction of the defrost timer, evaporator heater or defrost sensor. If the defrost system does not start, the evaporator becomes covered with ice, blocking the air flow.
Electronics diagnostics require a multimeter. It is necessary to “ring” the thermostat contacts at different temperatures. If the contacts do not open during defrosting, the part must be replaced.
⚠️ Attention: When replacing a thermostat, it is important to choose the right analogue. Different models have different sensitivity capillary lengths and temperature response ranges. Installing an unsuitable part will lead to incorrect operation of the refrigerator.
It is also worth checking the integrity of the door seal. If warm, humid air constantly enters the chamber, the system will operate in increased mode, which can cause freezing of the inlet pipes.
Diagnostic table for the location of freezing
To quickly determine the nature of the malfunction, use the following table. It will help narrow down the search for the problem before calling a technician.
| Location of freezing | Probable cause | Nature of compressor operation | Required actions |
|---|---|---|---|
| Return pipe at compressor | Thermostat is faulty, excess freon | Works without stopping | Replacing the thermostat, checking the filling |
| Filter drier and the beginning of the capillary | Moisture in the system, clogged | Cycically (it works, then it stops) | Purge the system, replace the filter |
| Start of the evaporator (locally) | Freon leak, microscopic blockage | Works constantly, no cold | Looking for leaks, soldering, refueling |
| Entire return line | Liquid freon (hydraulics) got in | Knocks, vibrates | Urgent shutdown, compressor repair |
| Evaporator in the No Frost chamber | Faulty defrost system | Works longer than usual | Checking the heating element, timer, sensors |
Analysis of the table shows that a visual inspection of the place of ice formation provides 50% of the information about the diagnosis. However, to accurately determine the pressure in the system, you need a manometric manifold.
Remember that the table is for reference only. In reality, faults can be combined: for example, a leak could lead to moisture and air entering the system, which caused a complex problem.
Algorithm of actions when a problem is detected
If you notice frozen pipes, do not panic, but act quickly. The first step should always be to completely defrost the refrigerator.
Unplug the appliance, open the doors and leave it for at least 24 hours. This is necessary so that ice plugs in hard-to-reach places (inside the evaporator channels) completely melt.
☑️ Primary diagnostic checklist
After switching on, check the operation of the unit for several hours. If ice appears again, the problem is of a technical nature and requires the intervention of a specialist.
Do not try to chip off the ice with a knife or other sharp objects. The thin walls of the evaporator tubes can easily be pierced, which will lead to the immediate release of all freon and the entry of air into the system.
⚠️ Attention: The use of hair dryers or heaters for accelerated defrosting is prohibited. A sharp temperature change can damage the plastic inner chamber box and cause deformation of solder joints.
If the refrigerator is under warranty, opening the rear casing yourself or breaking the seals on the compressor will lead to loss of warranty.
Prevention and operating rules
To minimize the risk of pipes freezing, it is important to follow the operating rules. Regularly check the condition of the rubber seals on the doors. If it does not fit tightly, excess moisture will enter the chamber.
Do not place hot foods in the refrigerator. The evaporation of a large amount of water leads to the rapid formation of a snow coat on the evaporator, which disrupts heat transfer and can cause freezing of the inlet pipes.
For refrigerators with manual defrosting, it is critical to carry out this procedure regularly, without waiting until the layer of ice becomes visually noticeable. A thick layer of ice acts as a heat insulator, forcing the compressor to work at its limit.
The myth of a “useful” layer of ice
There is a misconception that a small layer of ice is useful for keeping you cold. In fact, ice has a thermal conductivity 4 times worse than the aluminum evaporator, and only interferes with the cooling of food.
Keep an eye on the ventilation around the refrigerator. If the condenser (grid at the back) is clogged with dust or is pushed close to the wall, the efficiency of heat transfer drops, the pressure in the system increases, which can also indirectly affect operating modes and the formation of condensation.
Timely maintenance, such as cleaning the drainage hole in the chamber (if there is one) and checking the tightness of the doors, prolongs the life of the unit.
When you need to call a specialist
There are a number of situations when self-repair is not only ineffective, but also dangerous. If, after a complete 24-hour defrosting, the problem with freezing recurs during the first day of operation, you need a specialist.
Professional intervention is required when:
- 🛠️ Replacing the compressor: Requires soldering, vacuuming and precise filling.
- 🛠️ Eliminating leaks: Searching for fistulas in the foamed parts of the body is only possible using special equipment (nitrogen, leak detector).
- 🛠️ Replacement filter-drier: The procedure requires opening the circuit, which is impossible without a vacuum sealer.
The master has a set of tools, including vacuum pump, scales for refilling freon and a burner. Only with their help can the tightness and performance of the system be restored.
⚠️ Attention: Freon used in modern refrigerators (R600a) is an explosive gas. Work to replace the refrigerant should be carried out in a well-ventilated area away from sources of open fire.
An attempt to save on calling a technician for complex diagnoses (clogs, leaks) often leads to failure of the compressor, the cost of replacing which is up to 70% of the price of a new refrigerator.
Why does only one tube freeze, while the other is hot?
This is the normal physics of the process. One tube (discharge) carries hot gas from the compressor to the condenser, so it is hot. The second (suction) carries cold gas from the evaporator. If the suction tube becomes icy, this is a sign that the freon has not had time to completely transform into a gaseous state, which indicates a malfunction.
Is it possible to use a refrigerator if the tube is covered with ice?
For a short time - it is possible, but not recommended. Long-term operation in this mode will lead to liquid freon entering the compressor, which will cause its breakdown. It is better to defrost the unit and call a technician for diagnostics.
How much does it cost to repair if the tube is frozen?
The cost depends on the cause. Replacing the thermostat will cost the least. If leak detection, soldering and refilling with freon are required, the price will be significantly higher due to the labor intensity of the work and the cost of materials.
Does the amount of food in the refrigerator affect freezing?
Yes, indirectly. An empty refrigerator rises to temperature faster when the door is opened, causing the compressor to work more often. However, the main reason for freezing of tubes is still technical faults, and not loading of the chambers.