The refrigerator stopped freezing, and the compressor Does it hum but won't turn on or does it run non-stop? Often the reason lies in hydraulic blockage the capillary tube. This is the thinnest element of the refrigeration circuit, which is responsible for throttling the refrigerant and sharply reducing its pressure in front of the evaporator. Unlike simple filters, this unit has a microscopic diameter, which makes it vulnerable to moisture, copper oxides, or oil breakdown products.
An attempt to remove the blockage yourself requires not only accuracy, but also an understanding of the physics of the process. Freon circulates in the system under pressure, and the internal cavity of the tube must be perfectly clean and dry. Any mistake can lead to depressurization of the circuit or failure of the compressor, so before starting work you need to weigh your skills and the availability of tools.
In this article we will look in detail at how to diagnose the problem, what tools are needed for purge flushing the system, and whether it is even worth undertaking this repair at home. You will learn about the nuances of working with nitrogen, alcohol and a vacuum pump, without which high-quality cleaning is impossible.
Diagnostics: how to determine a clogged capillary tube
The first sign indicating hydraulic blockage, is uncharacteristic behavior of the compressor. It can start up, run for a few seconds, and then shut down via a thermal relay due to overload. In other cases, the motor hums, but there is no refrigerant circulation at all, which leads to a lack of cold in both chambers.
Touch the condenser (grid at the back) and the evaporator inside the refrigerator. If the grate is cold or only slightly warm at the compressor, but the inside is dry and free of frost, this is a sure sign. Also pay attention to the temperature of the compressor housing: when working on the “lock”, it heats up much faster than usual.
⚠️ Attention: If you hear gurgling or hissing, but cold does not appear, an ice plug of moisture may have formed in the system. This requires not just purging, but thorough evacuation and replacement of the filter-drier.
For accurate diagnostics, professionals use a manometric manifold. When the compressor is running, the pressure on the suction side will be close to vacuum, and on the discharge side it will be significantly higher than normal. However, at home, they often rely on indirect signs and experience.
- 🔊 The compressor hums, but quickly turns off or does not start at all.
- ❄️ The condenser (rear grille) remains cold when the motor is running.
- 🧊 Not in the freezer frost or it appears only at the entrance of the tube.
- 🔥 The compressor housing overheats in a short time of operation.
Necessary tools and materials for cleaning
Before you begin disassembling, make sure that you have all the necessary arsenal. Cleaning capillary tube is not just “blowing into it.” You will need to create a pressure exceeding the working one in order to push out the plug, and at the same time flush the system from dirt.
The main tool will be a cylinder with a dry nitrogen reducer. The use of oxygen or air from a compressor for tires is strictly prohibited, since the moisture and oil contained in them will lead to re-clogging or an explosive mixture with compressor oil.
You will also need technical alcohol (isopropyl or high-purity ethyl) to flush the circuit. Regular rubbing alcohol may contain water, which is unacceptable. To desolder copper tubes, you will need a gas torch, solder and flux.
- 🛠️ A cylinder with dry nitrogen and a high-pressure reducer.
- 🧪 Industrial alcohol or a special flushing solvent.
- 🔥 Gas torch, solder and flux for soldering copper connections.
- 🔧 Pipe cutter, rolling machine and a set of keys for dismantling.
Preparing the refrigerator for repair and disassembling the system
You should start by completely disconnecting the unit from the power supply. Let the refrigerator stand for several hours so that the pressure in the system equalizes and the oil drains into the compressor crankcase. This minimizes the release of oil during depressurization.
Next you need to gain access to the process pipe or independently cut the Schrader valve into the compressor processor tube. If you are planning a serious flushing, the system will have to be cut in the area of the filter-drier. Filter-drier - this is a consumable item, it will need to be replaced with a new one after completion of the work.
☑️ Preparation for cleaning
When cutting the tubes, be prepared for the fact that oil may pour out of there. Prepare containers for collecting it. It is important not to lose the tightness of the remaining parts of the system if you do not plan to touch them. All open ends of the tubes should be immediately closed with plugs or fingers to prevent dust and moisture from the air from getting inside.
⚠️ Attention: When soldering and working with an open flame, observe fire safety. Make sure that there are no flammable materials or refrigerant in the air nearby.
Cleaning methods: nitrogen purging and flushing
There are two main ways to clear the blockage: mechanical purging high pressure and chemical flushing. Often these methods are combined to achieve better results. Nitrogen purging allows solid particles and oil plugs to be pushed out.
To do this, nitrogen is supplied to the cut-off capillary on the compressor or condenser side. The pressure should be increased gradually, controlling the process. A sudden surge in pressure can rupture the thin walls of the tube or damage the evaporator. If the tube is clogged tightly, nitrogen may not pass through.
Safety precautions when working with nitrogen
The nitrogen in the cylinder is under enormous pressure (up to 150 atmospheres). The use of household gearboxes or the absence of a pressure gauge can lead to ruptured hoses and injury. Always use specialized equipment for refrigeration systems.
If purging does not help, flushing is used. Technical alcohol is poured into the circuit, which dissolves oily deposits and paraffin plugs. After this, the system is again purged with nitrogen to displace liquid and dirt. The process is repeated until the emerging liquid becomes clean.
- 💨 Blowing with nitrogen under pressure up to 20-30 atmospheres.
- 🧪 Filling with technical alcohol to dissolve deposits.
- 🔄 Cyclic flushing: alcohol -> nitrogen -> repetition.
- 👀 Visual control of the purity of the output stream.
Replacing the filter-drier and assembling the circuit
After successful cleaning capillary tube installation of a new filter-drier is mandatory. The old element is guaranteed to be clogged with dirt that you just washed out of the system and will no longer be able to effectively remove moisture. Ignoring this step will lead to re-clogging in a short time.
When soldering a new filter, it is important not to overheat its body, since there is zeolite inside, which loses its properties at high temperatures. Soldering should be done quickly using heat sink clamps or a damp rag wrapped around the filter housing.
| System element | Repair action | Reason for replacement/processing |
|---|---|---|
| Capillary tube | Blowing and washing | Eliminating hydraulic blockage |
| Filter drier | Mandatory replacement | Accumulation of moisture and dirt, loss properties |
| Compressor oil | Quality control | Checking for acidity and presence of suspended matter |
| Refrigerant (Freon) | Refilling after evacuation | Removed when the system is depressurized |
After installing all elements, soldering of connections is performed. The seams should be smooth, without solder sagging inside the tube. The quality of soldering directly affects the tightness of the system in the future. Any microcrack will lead to freon leakage.
Evacuation of the system before refueling
The most critical stage after assembly is vacuuming. Air and moisture that entered the circuit during repairs must be completely removed. Moisture at low temperatures turns into ice and will clog the capillary again, and the air will increase the condensation pressure, overloading the compressor.
To do this, a vacuum pump is connected to the system. The pumping process should last at least 30-40 minutes, and for systems with a long capillary - up to 1 hour or more. The residual pressure should be 0.1-0.2 mbar (or close to absolute vacuum according to the instrument readings).
Only after successful evacuation is the refrigerator refilled with freon. The amount of refrigerant must strictly correspond to the marking on the compressor or the label inside the refrigerator. A lack or excess of freon will negatively affect performance.
⚠️ Attention: The type of refrigerant (R134a, R600a) must strictly correspond to that for which the compressor is designed. Using the wrong freon can lead to destruction of the compressor or a fire (in the case of R600a fuel).
Frequent errors and risks of self-repair
Refrigeration circuit repair is a high-risk area. The main mistake beginners make is trying to clean the system by simply “blowing into it with your mouth” or using a car compressor. This drives moisture deep into the system, creating an acidic environment when mixed with oil, which kills the compressor from the inside. Another common problem is improper soldering. Overheating of the tubes leads to the formation of oxides (scale) inside, which in a month will fall off and clog the capillary again. Underheating leads to freon leaks. acidic environment when mixed with oil, which kills the compressor from the inside.
Another common problem is improper soldering. Overheating of the tubes leads to the formation of oxides (scale) inside, which in a month will fall off and clog the capillary again. Underheating leads to freon leaks.
It is also worth remembering about the fire hazard, especially if R600a freon (isobutane) was used in the system. It is highly flammable. Before any soldering, it is necessary to thoroughly ventilate the room and make sure that there is no smell of gas.
- ❌ Using moist air or oxygen for purging.
- ❌ Refusal to replace the filter-drier after opening the circuit.
- ❌ Insufficient vacuuming time system.
- ❌ Temperature violation when soldering connections.
FAQ: Frequently asked questions
Is it possible to clean the capillary tube without unsoldering it?
Theoretically, you can try to blow the system with nitrogen through process pipe, if there is access to both ends of the capillary. However, without removing the filter drier and washing with a solvent, the effectiveness of this procedure will be low. You simply push the plug further or into the condenser, from where it can return.
What is dangerous about using air from a compressor for tires?
The air always contains water vapor. When moisture enters the refrigeration circuit, it freezes in the capillary, forming an ice plug. In addition, oxygen in combination with compressor oil at high temperatures can cause oxidation and the formation of acids that corrode the system from the inside.
How much does it cost to clean the capillary in the service?
The cost depends on the region and model of the refrigerator, but usually consists of the work of overcooking the circuit, the cost of the filter-drier and refilling with freon. At home, you save on work, but you risk completely destroying the unit if you lack experience.
How to understand that the capillary has been cleaned?
When blowing with nitrogen, you should hear a smooth, strong flow of air coming out of the opposite end of the tube. If previously it was difficult to blow or did not blow at all, but now the flow is free, the blockage has been eliminated. However, this does not guarantee the operation of the refrigerator without evacuation and refilling.