The smallest metal particles and moisture seriously damage the compressor mechanism. During the installation of the system, copper chips and dust get inside the pipes. The working circuit goes through a vacuuming procedure, but it is not always possible to completely remove the contamination. Water droplets can remain on the pipe walls or get inside with hygroscopic synthetic oil. An air conditioner filter drier (FOC) allows you to protect an expensive unit from damage. When a resource is used up or a unit malfunctions, its replacement is required.
What is an air conditioner filter drier
The filter drier is an element of the working circuit of the climatic and refrigeration equipment. Its task is to remove liquid and acid from the refrigerant and prevent clogging of the capillary tube. The danger of the presence of water in the circulating freon is underestimated. It changes the properties of the oil used in the installation. The product decomposes to form acids. When the liquid freezes, the capillary tube closes, the suction pressure rises. The compressor overheats in an intensive mode of operation. The metal parts of the unit are corroded.
Moisture enters the air conditioner circuit in various ways:
- during the installation of the climate system;
- leak on the suction side;
- opening the circuit for service;
- the oil or refrigerant used when charging contains moisture.
Any deviations from the operating mode lead to breakdown or complete wear of the compressor. Installation of the FOC unit protects expensive equipment from interruptions in operation and wear of spare parts.
The assembly site is between the condenser and the capillary tube. When the climatic technology is turned on, the compressor starts working. The unit builds up pressure to compress the gas. The condensed refrigerant enters the filter drier in the liquid phase. The hydraulic resistance of the adsorbent is small, so the freon passes the unit unhindered. The principle of operation of an air conditioner dehumidifier is that the hygroscopic zeolite absorbs moisture from the refrigerant. A solid porous material absorbs water molecules, while larger particles of freon pass it freely. All models of split systems are equipped with filter driers that work according to the same scheme.
The type of desiccant is selected according to the type of freon and oil. For a system with a mineral product, the addition of active alumina is relevant. Polyester oils require an adsorbent that retains moisture well. Existing dirt particles are also captured by the filter. At the exit, the fine mesh prevents the zeolite granules from being carried away with the flow. FOK is located on the section of the line in front of the thermostatic valve. During installation, the arrow on the body must be in the direction of flow. The filter is a universal device, it cleans and dries freon.
The part is a metal cylinder 80-170 mm long and 16-30 mm in diameter. The dimensions of the unit depend on the model of the air conditioner into which it is inserted. The body is hermetically sealed by plasma welding to prevent refrigerant leakage. The surface is treated with an anti-corrosion compound. There are two copper pipes for refrigerant inlet and outlet. Metal or polyester nets are installed inside the case. A core filled with synthetic zeolite granules is placed between them.
In some models, an additional branch pipe is installed at the inlet.It is used to evacuate the system. One side of the core abuts against the perforated plate and the anti-vibration insert. The return part is fixed with a spring. A mesh is installed at the inlet to prevent zeolite granules from entering the condenser. The diameter of the adsorbent particles is 1.5-3 mm. At the exit there is a grid with smaller cells. Its purpose is to capture solids from freon.
Varieties of FOK design
Substances with varying degrees of moisture absorption are used as a desiccant. With the same body parameters, the difference in the volume of retained liquid reaches 30 g. There are several types of FOC:
- for installation on a liquid line;
- bi-directional or bi-flow filter - installed in either direction, has built-in check valves;
- combined options with a receiver;
- suction filter to remove acid.
The bi-directional version is designed for air conditioners operating in cooling and heating mode. In such models, check valves ensure the movement of freon from the outer edge to the center. Moisture and dirt particles are retained in the filter regardless of the direction of flow.
Some models are equipped with some kind of fuses inside the case. These are fusible links that are triggered when heated to 85-100 ° C. The part melts and releases the refrigerant.
Step-by-step instructions for replacing
The installation of a humidity indicator with a sight glass helps to monitor the condition of the dryer filter for an air conditioning compressor. The color of the device is used to determine the moisture content of the refrigerant. Green bars indicate normal. Coloring in yellow and the appearance of bubbles in the viewing window indicates clogging and a decrease in the efficiency of the unit. This is one of the reasons for replacing the filter drier. The detail changes in other cases:
- loss of tightness at the soldering point of the case;
- replacement of the compressor;
- opening the cooling system.
When the resource is depleted, the node is not restored, but cut out and replaced with a new part. The term of operation is indicated in the documents of the air conditioner. Manufacturers recommend replacing a part with any impact on the system. The cost of a dehumidifier is low, you should heed the advice of experts.
To do the job, you will need special tools:
- pipe cutter;
- Vacuum pump;
- gauge station;
- filling cylinder.
Freon is used as a consumable; the type of gas is indicated on the nameplate of the air conditioner and in the documents.
- Unsolder with a torch or cut off the worn part with a pipe cutter.
- Clean pipe ends to fit a new filter drier.
- Solder a new node. Welding, flux and solder are used. In the process of work, a protective gas is used, which removes heat from the place of soldering. Usually nitrogen is taken, it prevents overheating and destruction of the polyester mesh of the filter. The housing (arrow) is positioned in the direction of flow of the refrigerant. If the model is bidirectional, then it is set arbitrarily.
- The system is evacuated, the pump is connected via a gauge station. The operating time depends on the readings of the pressure gauge. The procedure removes air, pollution and moisture from the climatic equipment.
- Refrigerant is poured into the working circuit.
- The sealing of the system is checked.
- A test run of the equipment is being carried out.
Replacing the air conditioner dryer filter is associated with depressurization of the split system line. Assembly of the assembly requires expensive equipment and special skills. It is better to entrust it to professionals from the service center. Errors in the installation result in the failure of the compressor and other important parts of the air conditioning system.