Compressor replacement process

1. Put the refrigerant: open the high and low pressure valve with an Allen wrench.

Pay attention to the ventilation of the working environment to avoid suffocation;

The speed of discharging the refrigerant should not be too fast to prevent personnel from being frostbited by the refrigerant; at the same time, it can prevent the refrigerating oil in the compressor from being discharged with the refrigerant. Once the compressor is intact after subsequent inspection, the lack of refrigerating oil will affect 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 higher. 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;

Ignite the welding torch and adjust the flame to a neutral flame;

Use a welding gun to preheat the welding joint, after the welding joint solder is melted, draw out the suction and exhaust pipes;

3. No-load operation: the suction and exhaust pipes of the old compressor are open;

Compressor is powered on

Note: Before dismantling the old compressor, ensure that the suction and exhaust pipes are open and the running time does not exceed 5 seconds to determine whether the compressor unit is blocked and whether there is suction and exhaust.

To test whether the compressor has suction and exhaust, you can approach the exhaust port with your fingers to feel;

Old compressors with poor insulation and high 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 tube to the compressor suction and exhaust pipe, and then clamp the process tube to flat seal welding.

5. Cleaning system:

Spray the cleaning liquid into the condenser and evaporator, then blow in high-pressure air or nitrogen, repeat the above process two or three times, until the air blown out of the liquid is clean;

Blow in high pressure air or nitrogen from the opposite direction for more than 10 seconds

Note: The cleaning fluid requires high soluble oil and easy to volatilize. R11 is recommended;

It is necessary to ensure the cleanliness of the nozzle of the welding place; if the compressor oil is black or contains more impurities, the system should be cleaned and the liquid storage tank and filter should be replaced.

6. Replace with a new compressor: Place the compressor foot pads on the chassis bolts. The upper part of the rubber feet can be lubricated with a little detergent (not oiled); put in the compressor; screw the foot screws; pull out the compressor exhaust Pipe rubber plug; pull out the compressor suction pipe rubber plug.

In principle, it is required to use the original model of the original brand compressor, if it cannot be satisfied, the capacity of the new compressor must be consistent with the capacity of the old compressor;

Scroll compressor and rotor compressor cannot be interchanged;

Single-phase compressor and three-phase compressor cannot be interchanged;

To remove the rubber plug of the compressor, the exhaust pipe must be first followed by the suction pipe;

The maintenance process must ensure that the lubricating oil cannot touch.

7. Weld the new compressor: ensure that the welding nozzle is clean and oil-free, connect the copper pipe; fill the copper pipe with nitrogen; ignite the welding torch, and adjust the flame to a neutral flame; the flame should be as vertical as possible to the welding position, and do Z-shaped movement preheating ; When the surface of the copper pipe is reddish-brown, fill the weld with solder to penetrate into the weld, and withdraw the welding torch after the weld is covered.

Nitrogen must be filled for welding, and nitrogen must reach the welding position;

It is advisable to preheat until the copper tube turns pink;

The welding rod must be melted by the temperature of the copper pipe, not directly by the flame;

The welding quality should be full and shiny on the surface of the welding seam, and welding without burrs on the front edge 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 face the position of the terminal;

8. Leak detection for pipeline wrapping and welding

Special attention to press replacement: air running is highly dangerous

When the compressor is running, if the high-pressure side is blocked by welding and the low-pressure side leaks, it is very dangerous. The mixture of sucked air and refrigerating oil will ignite and explode when it reaches the flash point temperature under high temperature and high pressure.

How it happens: The compressor sucks in air, and somewhere on the exhaust side (such as a capillary tube, four-way valve, etc.) is blocked, the air is continuously sucked in and compressed, and the compressor overheats the refrigerator to vaporize and form a mixture of oil and gas. When the temperature and pressure reach a certain condition, the oil-air mixture ignites and burns! Temperature and pressure rise sharply! If the pressure exceeds the compressive strength of the shell (160～200kg/cm2), the shell will burst!

 Four-way valve replacement method

Before welding the four-way valve, you must wrap the four-way valve with a damp cloth and weld the four-way valve assembly completely. Pay attention to the direction of the flame during welding, and do not allow the flame to heat the valve body;

Submerge the four-way valve in the component in water for replacement (it is better to design a simple and suitable tooling). In order to control the relative angle between the four-way valve assembly pipeline parts, you can remove a pipeline part to reinstall a new valve After welding, disassemble and replace other pipe fittings. During the replacement process, ensure that the inside of the new and old four-way valves are not 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, you must wrap the four-way valve with a damp cloth, and pay attention to the direction of the flame during welding. The flame is not allowed to heat the valve body;

2. When replacing the four-way valve, because the copper tube has been welded many times, try to use silver-containing solder as much as possible. If there is no silver-containing solder, you can use copper-phosphorus solder when soldering with flux;

3. Care should be taken to avoid water entering the valve body when welding the four-way valve to cool;

4. When welding, when possible, it should be filled with nitrogen to protect it to reduce the generation of oxide scale. After welding, if possible, use nitrogen to clean the internal oxide scale of the four-way valve.

Judgment of the four-way valve in the refrigeration system of the air conditioner:

A. Fluorine is collected by refrigeration. When the fluorine is almost collected, the return gas has no temperature (that is, normal temperature). At this time, touch the two low-pressure pipes of the four-way valve by hand. If there is no obvious temperature difference, the four-way valve is normal (the two high-pressure pipes are of course very Don’t touch it if it’s hot), the low-pressure inlet pipe of the four-way valve of the series gas is at room temperature, and the outlet pipe (to the compressor) becomes obviously hot.

B. The four-way valve with air flow has a louder air flow sound.

C. Gas flow through the four-way valve will result in incomplete collection of fluorine, and the return pressure is about 0.1MPa or more.

Precautions for installation or maintenance of globe valves

1. The bell mouth of the indoor and outdoor connecting pipes must be aligned with the thread of the shut-off valve connector, and the nut should be tightened by hand. Generally, the thread of the connector must be screwed in by hand. Oil to facilitate manual screwing of the nut). If only 1 to 2 buckles are screwed in, it is necessary to check whether the joint thread is scratched or slipped;

2. After the air conditioner is installed online, the valve core and valve core nut must be installed on the valve body with a certain torque;

3. After the nut and the joint thread are tightened by hand, use a wrench to lock it. When the nut is full of all the buckles, twist half the buckle and tighten the nut.

4. When replacing the shut-off valve, before welding the shut-off valve, discharge the refrigerant in the system, and 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 failure due to damage to the circle;

5. When welding a new shut-off valve, in principle, it is required to put the shut-off valve in water before welding. Under special circumstances, the method of wrapping wet cloth can be used. Welding operation is not allowed without cooling;

6. Inch threaded globe valves are marked with 7/16", 5/8", 3/4", 7/8", 17/16", etc. on the valve body, and must be matched with copper nuts for connecting pipes Pay attention to the corresponding use of metric and imperial systems. The copper nuts of the connecting pipes with tapered surfaces on the outer surface of household air conditioners are all imperial nuts;

7. When the welding shut-off valve is cooled, care should be taken to prevent water from entering the valve body;

8. When welding, it should be filled with nitrogen protection if possible to reduce the generation of oxide scale. If possible after welding, a small amount of refrigerant can be used to flush the oxide scale of the shut-off valve weld.