Nine refrigerant leakage locations and solutions
1. Leakage of evaporator
There are many welds on the left and right sides of the evaporator, and there may be more leaks. The leak of the newly installed air conditioner is mainly due to the poor welding skills of the employees of the air conditioner manufacturer. Before the copper pipe was burnt red (the temperature did not reach 600℃～700℃), the welding rod was placed at the welding joint, the copper pipe and The solder fails to fuse together, resulting in pinched welding, slagging, and unevenness in the weld.
When the air conditioner is newly installed, open the shut-off valve of the outdoor unit to remove the air from the indoor unit. Sometimes the sound of the indoor unit evaporator leakage can be heard with ears. It can be seen that the air conditioner leaks, and the evaporator solder joints cannot be ignored.
If the evaporator is found to be leaking, it is best to remove it and weld it. In order to prevent the heat flame from deforming the plastic shell of the evaporator, it is impossible to explain to the user. The method of disassembly is:
(1) Identify the missing points and mark them.
(2) If there is refrigerant in the refrigeration system, the refrigerant must be stored in the outdoor unit first.
(3) Use two 8-inch or 10-inch wrenches to remove the connecting lock nut of the indoor unit, and remove the electrical box on the right side of the indoor unit.
(4) Remove the fixed pipe and splint on the rear side of the evaporator, and remove the left and right positioning screws of the indoor evaporator.
(5) Slightly lift the pipe 20 from the back of the indoor unit with the left hand to move the evaporator forward. After pulling out the evaporator 5cm with your right hand, rotate the evaporator 90 degrees with both hands and pull it out along the pipe. Pay attention to the operation with both hands and do not knock the fins down. After removing the evaporator, place it in a flat and clean place, and wipe off the oil spill with a dry cloth. The leakage point is welded with silver welding, after the pressure check is confirmed that there is no leakage, install the evaporator back to the indoor unit plastic frame in the reverse order of disassembly.
2. Leakage at the indoor unit connection
The air conditioner is operating normally, but the indoor unit does not blow out cold air, indicating that the refrigeration system is malfunctioning. If oil stains are found at the connection of the indoor unit, it indicates that the refrigerant is leaking. First use two wrenches to tighten the "nose" at the connection, then rub the foam with detergent and apply it, and check if there are bubbles blowing out of the connection. If not, you can add R22 gas refrigerant from the low pressure gas valve bypass nozzle, subject to low pressure 0.5MPa. Stop the machine and check the receiving area with the washing spirit. After 3 to 5 minutes, no bubbles are generated, indicating that the air leakage at the connection has been eliminated.
If R22 bubbles are generated in the leak detection with the detergent, it means that the pipe bell mouth is cracked or damaged, and the bell mouth must be remade. Before production, first turn on the power, set the cooling state with the remote control, and let the compressor run for 5 minutes. Then close the low-pressure liquid valve first, and then close the low-pressure gas valve after 40-50 seconds. At this time, touch the off button of the remote control to stop the air conditioner. Use two 10-inch wrenches to unscrew the lock nut at the connection of the indoor unit, check the damage of the bell mouth and analyze the cause of the leakage, so that you can accumulate more maintenance experience.
The method of making the bell mouth is: use a cutter to remove the original damaged bell mouth, then put the copper pipe into the pipe expansion chuck of the same caliber of the special pipe expander, and tighten the nuts on both sides. The upper mouth of the copper pipe needs to be higher than 1/3 of the slope of the bell mouth. File the mouth of the copper pipe flat with a file. And remove the burrs inside the nozzle. Dip the copper scraps from the copper pipe with a soft cloth to prevent the copper scraps from being mixed into the refrigeration system and causing the filter to be blocked, which may enlarge the fault.
After visually observing that the pipe mouth is flat, press the pipe expansion cone of the ejector on the pipe mouth, hold the pipe expansion chuck with the left hand, and tighten the pipe expansion cone handle of the screw with the right hand. The action should be even and slow, screw in 3 For 5 reasons, turn back 2/5 times and repeat until the nozzle can be expanded into a 90o+0.5 bell mouth shape. The bell mouth produced by this operation method is round, smooth and without cracks. Note that when expanding the bell mouth, the chuck must clamp the copper tube firmly, otherwise, the copper tube will easily move back when the mouth is expanded, resulting in insufficient height or deflection of the bell mouth, and it is still easy to leak refrigerant after connection.
After the bell mouth is made, align the lock nut with the screw buckle by hand, and then tighten it with a wrench according to the torque requirement. After the pipeline is connected, how to exhaust the air in the evaporator and the connecting pipe is an operation link that beginners must master. If the emptying is not good, a large amount of air will be mixed in the system, which will cause the entire refrigeration system to work abnormally and cause failures such as reduced cooling capacity, increased current, increased pressure, and shortened compressor life.
Moisture in the air enters the system and reacts with the refrigerant, which will increase the corrosiveness of the system, promote the aging of the compressor coil, destroy the insulation strength, increase the flash point of the lubricant, and shorten the service life of the compressor. Therefore, removing the air in the evaporator and pipeline is a key link that the maintenance personnel must master.
The method of exhaust is to loosen the low-pressure gas lock nut by half a turn, use an Allen key to open the low-pressure liquid shut-off valve for about 1/2 turn, and close it immediately after hearing the "hissing" sound from the low-pressure gas. When the "hiss" sound of the bottom pressure gas shut-off valve disappears, open the low-pressure liquid shut-off valve for 1/2 turn, and close it immediately after 15 seconds. Repeat the operation 3 times to drain the air. The specific operation frequency and length of time should be used flexibly according to the size of the evaporator and the length of the pipeline. Some maintenance personnel do not loosen the low-pressure gas lock nut when emptying, but exhaust the air from the bypass nozzle, which is not advisable.
Three, outdoor unit stop valve core leakage
Most of the leakage of the stop valve core of the outdoor unit occurs after the machine is moved. Due to the switch valve shaft rotating in and out, and the rubber ring is aging for a long time, the outer sealing rubber ring of the shaft is worn out, causing the stop valve to leak. , A small bubble can be found in about 3 minutes. By adding an asbestos round gasket in the secondary sealing cap, small leaks can be eliminated. If the leakage is serious and you can hear a "hissing" sound, the refrigerant can be discharged from the low-pressure gas lock nut of the outdoor unit. When venting, there should be a refrigerant with a pressure of 0.1 MPa in the pipe to prevent the system from entering air and causing the trouble of vacuuming.
The operation method is: remove the stop valve stop ring with needle-nose pliers. Use an Allen wrench to unscrew the shut-off valve screw, plug the leak with your left hand, and quickly coil the raw material tape around the screw buckle and sealing ring with your right hand for 4 turns, and quickly turn the shut-off valve screw to install the snap ring. Then wind the raw material tape around the secondary sealing thread buckle for 2 to 3 turns, and put on the secondary sealing cap.
Add F22 refrigerant from the filling point of the low-pressure gas stop by-pass valve. When the gauge pressure reaches 0.3MPa, use the remote control to turn on the device, and continue to add R22 gas to 0.45MPa. When adding gas, it should be added slowly and not too hastily, lest R22 gas increases and the maintenance cost increases. After adding enough R22 gas as required, stop the air conditioner for 3 to 5 minutes. After the refrigerant gas in the system is balanced and the pressure rises, use the washing spirit to detect leaks at the second sealed outer cap. Confirm that there is no leakage, indicating that the raw material tape wound around the shut-off valve screw is well sealed, and the air leakage fault is eliminated.
Four, outdoor compressor U-tube leakage
Leakage of the U-shaped exhaust pipe of outdoor compressors is more common. The main reason is that the copper pipe has a thin wall and poor material. After bending into a U-shaped bend, small cracks appear. The vibration generated by the compressor during work makes the cracks larger. . Most of this kind of leakage failure will leak the gas, and it will be discovered after inspection when there is no cold air from the indoor unit.
The maintenance method is: wipe the leaking oil trace with a soft cloth, and weld the leaking part of the copper pipe with silver welding. Before welding, it is best to find a section of copper pipe that is thicker than the outer diameter of the exhaust pipe, cut it with a hacksaw, and wrap it around the crack to prevent leakage from there due to vibration.
Do not remove the U-shaped tube during maintenance, as that will make the high temperature and high pressure refrigerant gas discharged from the compressor directly enter the condenser, which will reduce the heat dissipation of the condenser and the cooling capacity. At the same time, the compressor will vibrate when working. After the U-tube is welded, add R22 gas from the bypass nozzle of the low-pressure gas stop valve. Pressure test and leak detection. If no bubbles are blown out from the weld, it means that the U-tube leakage has been eliminated.
5. Outdoor unit capillary vibration and leakage
The air conditioner is not cooling, and the reason for the refrigerant leakage may be the vibration generated when the compressor is working, which makes the two pipes resonant friction, wears out the pipe wall, and causes the refrigerant to leak light.
Example: A Hisense KFR-33GW split air conditioner is not cooling, and the capillary tube is found to be worn and leaked. The elimination method is: cut the 6mm red copper tube with a saw, wrap it in the capillary leak, and then solder it with silver solder. Capillary tubes with the same inner diameter and specifications can also be replaced. Before replacing the welding, there should be no flammable and explosive materials within 1.5m. The back of the capillary should be covered by an iron plate.
When welding, the flame should not be too large, and it is better to use a neutral flame, the temperature reaches about 600℃, and quickly put the silver electrode into the welding mouth. The solder and the copper tube melt together, and the welding torch quickly leaves, otherwise the capillary will be blown. This technique requires maintenance personnel to slowly understand during welding and gradually master the welding technology.
Six, low-pressure bypass valve core leakage
The refrigeration system of split air conditioner supplements refrigerant (commonly known as "fluorine addition"), which must be refilled from the low pressure bypass. Use the gas filling pipe with thimble to open the low pressure gas filling valve stem, the r22 refrigerant gas of the refrigerant cylinder and the air conditioner refrigerant gas are connected, and the filling can be carried out.
The reason for the valve core leakage is: the thimble of the gas filling pipe is adjusted too long, and the thimble of the bypass valve cannot bounce back after being pushed in, so that the valve core cannot be reset. The troubleshooting method is to insert the key of the special air conditioner into the refueling valve core, give the valve core a force to make the valve core spring pop out, and the valve core leakage fault can be eliminated.
Seven, compressor terminal leakage
According to experience, the compressor terminal is leaking, which accounts for more than 2% of the leakage fault. Remove the overcurrent and overheat protector cover. If you see oil traces around the compressor terminal, it means there is a leak.
The method to eliminate is: first unplug the power plug of the air conditioner, and write a note "Someone repaired the air conditioner on the roof, plug in the power supply" and hang it on the socket. To prevent maintenance personnel from repairing the outdoor compressor on the top floor; indoor personnel plugged in the power source by mistake, causing personal electric shock. Then use the F22 meter to test the pressure of the system at the low pressure gas refueling bypass valve.
If the pressure in the system is zero at this time, you can first charge the system with a refrigerant gas at a pressure of 0.3MPa, so as to avoid no pressure in the system. When the detergent is used for leak detection, the detergent enters the compressor oil through the leak point, causing compression Axle hung accident. The pressure gauge test system is under pressure, and the foam can be rubbed out by the washing spirit to check the leakage point of the terminal with one word to change who will make a mark. Wipe clean the oil stains around the terminal with a dry cloth and alcohol, and use sandpaper to polish out new ballast around the terminal, and then mark the new ballast with a hacksaw blade to facilitate the adhesion of the adhesive. At this time, let off the gas in the system, connect the vacuum pump, and evacuate the system. When the system pressure reaches minus 0.1MPa, use C31 double-tube glue to prepare it at a ratio of 1:1 and apply it to the wiring.
Because the refrigeration system is in a vacuum state, the C31 glue penetrates into the leakage point. After the leakage point is coated, a 100W bulb is required to bake the glued place for 30 minutes to make the glue more likely to penetrate into the leakage point. Note that the distance between the bulb and C31 glue should not be too close, 20cm away from the C31 glue is appropriate, otherwise the glue will be baked and flowed around the compressor, which will reduce the leakage plugging effect. After the compressor terminal is glued for 2 hours, it can be suppressed and leaked. Finally, evacuate, add fluorine to test the machine, and resume refrigeration.
8, the pipeline is concave and leaking
Four deflated pipelines often appear after home renovation. Some decoration workers don't understand that there is refrigerant in the refrigeration pipeline; it is easy to bend, because there is an insulation sleeve outside the pipeline, it is not easy to be found after bending. After the pipeline collapsed, the refrigerant leaked, and the system was turned on again to add fluoride, and the refrigeration system showed two shut-off symptoms.
Example: A KRR-32GW split air conditioner is not cooling. Use the pressure gauge to test the pressure. The pressure gauge shows negative pressure. After the gas is added to 0.45MPa, the noise of the compressor increases, and there is no cold air blowing out of the indoor unit. Remove the casing of the indoor unit, touch the evaporator by hand, it is not cool, peel off the indoor unit pipeline insulation sleeve, found that the low-pressure liquid pipe is concave. Use a cutter to remove the concavity and interception point, and use the method of butt joint with outer sleeve. After soldering with silver welding, press again, check for leaks, evacuate, add fluorine, and turn on the machine with the remote control. However, the air conditioner continues to show the above symptoms, indicating that there are two interceptions in the pipeline. Continue to peel off the outdoor pipeline insulation sleeve, and found that the outdoor pipeline low pressure gas pipe was also dented. After the outdoor pipeline is trimmed and welded, turn it on with the remote control, and the air conditioner resumes cooling.
Nine, four-way reversing valve leakage
There is more leakage at the angles of the three copper pipes under the four-way valve of the heating and cooling type air conditioner. The repair method is: first wipe off the oil stains at the corners with a towel, and use a detergent to check for leaks, mark the leaks with a steel needle, then release the refrigerant, and wrap the four-way reversing valve with a wet towel cool down. When welding, you must master the flame technology by yourself, aim at the leaking point, and quickly spot the silver electrode when the angle reaches the welding temperature. The operation method should be fast, and the welding should be successful once and the pressure test should not leak.
For beginners who encounter the leakage of the included angle of the four-way reversing valve, it is best to use the glue method to repair the leakage. Due to the close angle between the nylon spool slider and the leakage point, and the overhead welding is difficult, improper operation will cause the spool to bake and deform. Once the four-way valve slide block blows air, the air conditioner does not control the heat and cold, and the original minor leakage becomes a major failure that cannot be replaced by the four-way valve. This has caused time and economic losses to users. The four-way valve angle gluing method is the same as the compressor gluing method. After pressure testing, leak detection, evacuation, and fluorine addition, the angle leakage of the reversing valve of the air conditioner can be eliminated and the refrigeration can be restored.
