First, the compressor replacement process
1. Put the refrigerant on: Open the high and low pressure valve with an Allen key.
Pay attention to the ventilation of the working environment to avoid suffocation;
The speed of the refrigerant should not be too fast, so as to prevent the personnel from being frosted by the refrigerant. At the same time, the refrigeration oil in the compressor can be prevented from being released with the refrigerant. Once the compressor is inspected and completed, the lack of refrigeration oil will affect the normal use. Pay attention to the color of the refrigerant spray. If the spray is white or colorless, the internal cleanliness of the system is high. The compressor may not be damaged.
2. Remove the suction and exhaust pipe: confirm that the refrigerant has been exhausted;
Fill the system with nitrogen;
The torch is ignited to adjust the flame to a neutral flame;
Preheating the welding joint with a welding torch, and after the solder joint is melted, the suction and exhaust pipes are taken out;
3. No-load operation: the nozzle of the old compressor suction and exhaust pipe is open;
Compressor running
Note: Before the old compressor is removed, ensure that the operating time of the suction and exhaust pipe is open, the running time is less than 5 seconds, and it is judged whether the compressor unit is blocked or not.
Test whether the compressor has suction and exhaust, and the finger can be felt close to the exhaust port;
Old compressors with poor insulation withstand voltage and large operating current may leak electricity and cannot be tested in this way.
4. Remove and dispose of the old compressor:
Remove the old compressor, weld the process pipe to the compressor suction and exhaust pipe, and then flatten the process pipe clamp.
5, cleaning system:
Spraying the cleaning liquid into the condenser, the evaporator, and then blowing high-pressure air or nitrogen, repeating the above process two or three times until the air is blown out of the liquid;
Blow high pressure air or nitrogen from the opposite direction for more than 10 seconds
Note: The cleaning solution requires high oil solubility and is easy to volatilize. It is recommended to use R11;
The nozzle at the weld must be cleaned; if the compressor oil is black or contains more impurities, clean the system, replace the reservoir and filter.
6. Replace the new compressor: put the compressor foot pad on the chassis bolt, the upper part of the rubber foot can be lubricated with a little detergent (cannot be oiled); put in the compressor; screw the foot screw; pull the compressor exhaust Pipe rubber plug; pull the compressor suction pipe rubber plug.
In principle, it is required to use the original brand original compressor. If it is not enough, it must ensure that the new compressor capacity is consistent with the old compressor capacity;
The scroll compressor and the rotor compressor are not interchangeable;
Single-phase compressors and three-phase compressors are not interchangeable;
Pull the compressor rubber plug before the exhaust pipe and the suction pipe;
The repair process must ensure that the lubricant is not in contact.
7. Welding new compressor: ensure that the welded pipe mouth is clean and free of oil, connect the copper pipe; fill the inside of the copper pipe; the torch is ignited, and the flame is adjusted into a neutral flame; the flame is welded as far as possible to the vertical position, and the zigzag movement is preheated. When the surface of the copper tube is reddish brown, solder is added to the weld to infiltrate the weld, and the weld gun is withdrawn after the weld is filled.
Nitrogen welding must be done and nitrogen is guaranteed to reach the welding position;
Preheating until the copper tube turns pink is appropriate;
The electrode must be melted by the temperature of the copper tube instead of being directly melted by the flame;
The welding quality is full and lustrous on the surface of the weld, and no batch front burr welding is suitable;
Do not burn to the root of the suction and exhaust pipe during welding. The terminal cover needs to be removed after the welding process, and the flame direction cannot be opposite to the terminal position;
8, pipeline bandage welding leak detection
Special attention to press replacement: high risk of air operation
When the compressor is running, such as high-voltage side plugging and low-pressure side leakage is very dangerous, the mixture of the inhaled air and the refrigerating machine oil will spontaneously explode when it reaches the flash point temperature under high temperature and high pressure.
The principle of occurrence: the compressor draws in air, somewhere on the exhaust side (such as capillary tube, four-way valve, etc.) is blocked, the air is continuously sucked and compressed, and the compressor superheats the freezer to form a mixture of oil and gas. When the temperature and pressure reach certain conditions, the oil and gas mixture will burn and burn! Temperature and pressure rise sharply! If the pressure exceeds the compressive strength of the housing (160 ~ 200kg / cm2), the shell will burst!
Second, four-way valve replacement method
Before welding the four-way valve, the four-way valve must be wrapped with a damp cloth, and the four-way valve assembly should be welded under the whole. Pay attention to the direction of the flame during welding, and do not allow the flame to heat the valve body;
The four-way valve in the assembly is submerged in water for replacement (it is best to design a simple and applicable tooling). In order to control the relative angle between the four-way valve assembly, it is possible to remove a new pipe and reinstall the new valve. After welding, replace the other pipe parts. During the replacement process, the inside of the new and old four-way valve should not be burnt out, to ensure the welding quality of the new valve and the analysis effect after the old valve is returned;
1. When installing the four-way valve assembly, the four-way valve must be wrapped with a damp cloth, and the direction of the flame during welding is not allowed, and the flame is not allowed to heat the valve body;
2. When replacing the four-way valve, because the copper tube is welded many times, try to use silver-containing solder. If there is no silver-containing solder, use copper-phosphorus solder to add flux to weld;
3. Care should be taken to avoid water entering the valve body when cooling the welded four-way valve;
4. When welding, it should be filled with nitrogen gas protection when possible to reduce the generation of scale. After the welding is completed, the internal oxide scale of the four-way valve should be purged with nitrogen.
Judgment of the four-way valve in the air conditioner refrigeration system:
A. Refrigeration and fluoride recovery, there is no temperature when returning to the gas (that is, normal temperature). At this time, the two low-pressure pipes of the four-way valve are touched by hand. There is no obvious temperature difference for the four-way valve. (The two high-pressure pipes are of course very The heat does not need to touch), the low-pressure inlet pipe of the three-way valve of the string gas is normal temperature, and the outlet pipe (to the compressor) is obviously heated.
B. The three-way valve of the string gas has a large airflow sound.
C. The four-way valve series gas will lead to the end of the collection of fluorine, the return pressure is about 0.1MPa or more.
Third, the valve installation or maintenance precautions
1. The inner and outer connecting pipe bells must be aligned with the thread of the shut-off valve joint, and the nut should be tightened by hand. The joint thread is generally screwed by hand to enter more than 3 buckles to allow the use of a wrench to tighten the nut (you can wipe some frozen parts in the threaded part) Oil, in order to facilitate the manual screwing of the nut), if only the 1 to 2 buckle is screwed, the joint thread must be checked for scratches and slipping;
2. After the air conditioner is installed online, the valve core and the valve core nut must be mounted on the valve body with a certain torque;
3. After the nut and joint thread are manually tightened, use a wrench to lock. When the nut is full of all the teeth, turn the half fastener and tighten the nut.
4. When replacing the shut-off valve, before the shut-off valve is welded, first release the refrigerant inside the system, then wrap the shut-off valve with a damp cloth, pay attention to the direction of the flame during welding, and do not allow the flame to heat the valve body to avoid sealing. Analysis of the cause of the damage caused by the ring damage;
5. When welding a new shut-off valve, in principle, it is required to put the shut-off valve into the water to be welded. In special cases, the method of using a damp cloth can be used, and the welding operation is not allowed without cooling.
6. Inch thread stop valve has 7/16'', 5/8'', 3/4'', 7/8'', 17/16'' and other markings on the valve body. Note that the metric system is used correspondingly, and the copper nuts of the connecting pipe with the tapered surface on the outer surface of the household air conditioner are all English nuts;
7. When the welding stop valve is cooled, care should be taken to prevent water from entering the valve body;
8. When welding, it should be filled with nitrogen gas protection when possible to reduce the generation of scale. If possible after welding, a small amount of refrigerant can be used to flush the scale of the weld at the weld of the shut-off valve.
The difference between the air conditioner compressor string gas and the four-way valve string gas.
The air conditioner replaces the whole process of the four-way valve.
Air conditioning copper tube welding technology.
Air conditioning repair welding technical guidance.
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