Don't be afraid if the refrigeration system is clogged. Here are retrieval and cleaning methods
Typical features of clogging
1. The refrigerator or air conditioner does not cool for a long time.
2. The suction pressure drops, and even a vacuum state (negative pressure) occurs.
3. The compressor load is reduced, the motor operating current is reduced, and the compressor vibration and noise are reduced.
4. The ear is close to the outer wall of the refrigerator or air conditioner, and no sound of refrigerant flowing can be heard.
5. Serious frost behind the expansion valve.
The system is clogged or the refrigerant flow is not smooth, and the failure characteristics of the reduced refrigerant circulation are the same as the above, except that the severity is less severe.
Classification of clogging
1. "Fouling"
There are dirt in the refrigeration system, such as copper chips, welding slag, dust and other clogging.
2. "Ice blocking"
When the water vapor in the refrigeration system passes through the throttling, the temperature quickly drops to the freezing point, resulting in freezing, which blocks the capillary or throttling mechanism.
Dry filter clogged
Dry filter clogging is often not completely blocked. In addition to the "fouling" feature, it is characterized by condensation or frost on the capillary. This is because the filter plays a role in connection with the flow, and the capillary is equivalent to the evaporator- Endothermic and dew. Just replace the filter.
1. Inspection and elimination of "fouling"
The clogging of capillaries, filter driers and other pipes in the refrigeration system of refrigerators or air conditioners due to dirt is called "fouling."
1. The cause of "fouling": the stolen goods remain in the system during manufacture, the metal oxides in the system pipes fall off, the stolen goods are sealed into the system during the repair process, and the molecular sieve or silica gel powder in the filter enters the capillary.
2. The elimination method of "fouling": mostly occurs in capillaries and filters. The filter should be replaced after clogging. When the capillary blockage is inconvenient to replace, it can be flushed with nitrogen with a pressure of about 1MPa. Nitrogen enters from the end of the air return tube (evaporator) and is discharged from the condenser (or directly discharged from the capillary). Use your hand to press and hold the condenser vent, and then quickly disengage to increase the impact on the capillary. The "dirty clogging" of the capillary tube often appears at the inlet end, and the exposed part of the capillary tube is completely replaced, which is very effective in most cases. (Hint: In any case, the filter should be replaced when cleaning the capillary!)
2. Inspection and elimination of "ice jam"
Due to the presence of water vapor in the refrigeration system, when the evaporation temperature of the refrigerant is lower than 0 ° C, the water vapor is trapped at the outlet of the capillary to form ice beads, and the capillary blockage is called "ice blockage".
Typical characteristics of "ice blockage": After the "ice blockage" fault occurs, the characteristics of the refrigerator are the same as those of the complete "fouling block" (the characteristic of the air conditioner is that some evaporators are not cooled). The difference between the two is; "fouling" "Blocking" is long-lasting and will not disappear by itself. "Blocking of ice" changes with temperature and will only occur when the refrigerant is below 0 ° C. When the ice beads melt, the "blocking of ice" disappears by itself.
3. The source of moisture in the refrigeration system
1. There is a leak in the low-pressure part of the refrigeration system, and the refrigerant leaks seriously. After the compressor is running, a negative pressure appears in the low-pressure part, and a large amount of air is sucked in, thereby bringing water vapor.
2. After the refrigeration system is opened, it communicates with the atmosphere, and the storage time is too long so that the refrigerant absorbs the moisture in the air.
3. When replacing large components such as compressors and evaporators, the moisture in the components is not removed and sealed into the system.
4. Meters, hoses, gas cylinders and other tools used to fill the system with refrigerant contain moisture. The water content of the refrigerant exceeds the standard.
5. The vacuum degree is not high enough when the system is evacuated. There is still a lot of air and moisture in the system.
4. The elimination method of "ice jam"
Eliminating the "ice blocking" failure is essentially trying to expel water vapor from the system. After the "ice blockage" appears, the dryer has failed and should be replaced.
1. Exhaust baking: The ability of mechanical vacuum pumps to remove water vapor is very weak, and it is difficult to remove water vapor for a long time. Therefore, it is the most effective and scientific method to remove moisture while baking vacuum and heating the refrigeration system in an all-round way. There are various baking methods, such as heating the evaporator with a hair dryer or electric iron, and heating the condenser and filter with a blowtorch flame.
2. After the system is evacuated: fill the system with nitrogen at a certain pressure, then start the compressor to run for a while, and then release the nitrogen. Repeating two or three times can basically eliminate "ice blockage".
Cleaning of refrigeration system
The circulation of refrigerant in the refrigeration system should be kept free of impurities, moisture and air. After the compressor is burned, the acidity of the freezing oil inside the system will increase, and the tar smell can be smelled when the system connection pipe is cut. If the old refrigeration oil is not cleaned, it will cause corrosion of the new compressor coil used after replacement. The new compressor will burn again soon. Therefore, it is necessary to disassemble the refrigeration system and clean each component one by one.
1. Cleaning of pipelines
1. Copper tube: first blow with compressor air with a flow rate of 10-15 m / s, then corrode with 15% -20% hydrofluoric acid solution for 3 hours, then use 10% -15% soda aqueous solution and heat in turn Rinse with water and finally dry for 3-4 hours at a temperature of 120-150 ° C. In order to remove water vapor, it must be blown dry with nitrogen or dry air.
2. Steel pipe: First inject 5% sulfuric acid solution into the pipe and keep it for 1.5-2 hours, then inject 10% anhydrous sodium carbonate solution for neutralization, then rinse with clean water and blow dry with nitrogen or dry air, and finally use 20% Sodium nitrite purification.
3. Capillary tube: First remove the oil stain in the tube with a high temperature of about 650 ℃, blow it off with compressed air after cooling, then rinse with carbon tetrachloride, and finally blow dry with nitrogen or dry air.
2. Cleaning of condenser and evaporator
The heat exchange devices such as the condenser and evaporator of the air conditioner and small refrigeration equipment can also be cleaned by the above method, but if the aluminum evaporator and the composite rigid tube cannot be pickled, they can only be washed with trichloroethylene, and then Blow dry with nitrogen or dry air.
Cleaning the outer surface of air-cooled condenser
The outer surface of the air-cooled condenser is prone to dust and oil stains, which will block the air circulation, cause poor ventilation and affect the cooling effect of the air conditioner.
Scrubbing method: 70 ℃ warm water is required for scrubbing, a little detergent is added, and the surface of the condenser is rinsed with a special cleaning machine. a period of time. Let the detergent slowly remove the oil on the condenser, and finally rinse the detergent with clean water. If the oil is too thick, you need to use special tools to clean it.
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