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All the refrigeration system are designed to run without moisture and non-condensable gases else it may not work as designed and is likely to fail prematurely.

Presence of moisture in the air conditioning system may lead to the formation of acidic sludge in the oil and may cause restrictions on various places like expansion valve and evaporator coils thereby reducing the overall cooling effect.

Refrigerant liquid meter group copper valve body, refrigerant model: R12.R134.R410

In case of a hermetic compressor, it may cause deterioration of the insulation winding which may lead to short circuit and compressor motor burn out.

Non-condensable gases are just air which can enter during refrigerant charging, repair or maintenance. These gases take up space in the condenser and limit the amount of liquid refrigerant leading to reduced cooling efficiency.

Evacuation is carried out by using a vacuum pump and a recovery bottle, ones the system evacuates we need to wait for about 20-25 min to check the pressure gauge is holding the negative pressure (vacuum) as shown in the image.

This process may ensure that there are no leakages in the system as chances are air or moisture could enter via pipe cracks or leaky gasket or joints while performing evacuation procedure.

Because R22 and R410A have different compositions and pressures, R410A needs to be filled in liquid, and the thickness of the copper tube of the machine is also different, so it is forbidden to mix the two refrigerants. Maintenance measuring instruments and quantitative refrigerant charging equipment should also be dedicated.

According to the air-conditioning installation or maintenance process (national standard or industry-related standard): when the connecting pipe between indoor and outdoor units of air-conditioning installation exceeds the standard length by more than 5 meters, the refrigerant should be refilled in time. The operation effect is not good.

Quick Connector

R410A is a HFCs refrigerant mixed with two working fluids of R32 and R125 at a mass fraction of 1:1. Compared with R22, the condensation pressure of R410A is about 1.6 times that of R22. It is a high-pressure refrigerant and needs to improve the pressure resistance of the system. Compared with R410A, the saturation pressure of R32 refrigerant is about 2.5% higher.

Ten prohibitions on installation and maintenance of flammable refrigerant air-conditioning

1. It is strictly forbidden to engage in special operations without qualification certificates;

2. It is strictly forbidden to work at altitudes above 2m without wearing a safety belt or a safety rope;

3. It is strictly forbidden to smoke at the installation and maintenance site, and there should be no fire or high temperature heat source within two meters;

4. It is strictly prohibited to install without vacuuming or the vacuuming time is less than the specification requirements;

5. It is strictly forbidden to replace nitrogen with oxygen to maintain system pressure;

6. It is strictly forbidden to start and run the outdoor unilateral machine;

7. It is strictly forbidden to conduct welding repairs and use open flames or pipes with refrigerant in the welding system in the user's home;

8. It is strictly forbidden to recover the refrigerant under the negative pressure of the system, and the recovery time shall not exceed 1 minute;

9. It is strictly forbidden to use fake refrigerants, inferior refrigerants and different types of refrigerants to mix or substitute;

10. It is strictly forbidden to detect the system pressure in the startup state. In the standby state, the detection system pressure range is normal, and it can be powered on when there is no negative pressure.

Because R22 and R410A have different compositions and pressures, R410A needs to be filled in liquid, and the thickness of the copper tube of the machine is also different, so it is forbidden to mix the two refrigerants. Maintenance measuring instruments and quantitative refrigerant charging equipment should also be dedicated.

According to the air-conditioning installation or maintenance process (national standard or industry-related standard): when the connecting pipe between indoor and outdoor units of air-conditioning installation exceeds the standard length by more than 5 meters, the refrigerant should be refilled in time. The operation effect is not good.

Quick Connector

R410A is a HFCs refrigerant mixed with two working fluids of R32 and R125 at a mass fraction of 1:1. Compared with R22, the condensation pressure of R410A is about 1.6 times that of R22. It is a high-pressure refrigerant and needs to improve the pressure resistance of the system. Compared with R410A, the saturation pressure of R32 refrigerant is about 2.5% higher.

Ten prohibitions on installation and maintenance of flammable refrigerant air-conditioning

1. It is strictly forbidden to engage in special operations without qualification certificates;

2. It is strictly forbidden to work at altitudes above 2m without wearing a safety belt or a safety rope;

3. It is strictly forbidden to smoke at the installation and maintenance site, and there should be no fire or high temperature heat source within two meters;

4. It is strictly prohibited to install without vacuuming or the vacuuming time is less than the specification requirements;

5. It is strictly forbidden to replace nitrogen with oxygen to maintain system pressure;

6. It is strictly forbidden to start and run the outdoor unilateral machine;

7. It is strictly forbidden to conduct welding repairs and use open flames or pipes with refrigerant in the welding system in the user's home;

8. It is strictly forbidden to recover the refrigerant under the negative pressure of the system, and the recovery time shall not exceed 1 minute;

9. It is strictly forbidden to use fake refrigerants, inferior refrigerants and different types of refrigerants to mix or substitute;

10. It is strictly forbidden to detect the system pressure in the startup state. In the standby state, the detection system pressure range is normal, and it can be powered on when there is no negative pressure.

 observe the bubbles in the sight glass for refrigerant fillin

This method does show that there are bubbles that indicate a lack of refrigerant, but we must understand that the pressure loss of the liquid pipe can also cause bubbles. If the pressure loss of the liquid pipe is large, the liquid Refrigerant charging pipe will flash into a gas, and the flash gas will reduce the flow of the refrigerant when flowing through the expansion valve and erode the expansion valve. If the subcooling of the system is small, the pressure loss can easily generate bubbles seen in the sight glass. Remember, if there is no liquid but steam, it will be transparent when seen in the sight glass.

Other

If the refrigeration engineer with experience or careful observation will find that when the system is charged correctly, bubbles or flashes can also be seen in the sight glass. This is because the resistance in the liquid pipe in front of the sight glass causes a pressure drop, causing the refrigerant to flash. If the expansion valve is unstable or fluctuates with liquid, the expansion valve opens sharply, and the flow rate increases to produce enough pressure drop to cause the outlet of the liquid reservoir to flash. The sudden change in condenser pressure is also the cause of flash.
For example: a sudden change of the fan speed in a cold storage can easily change the condensing temperature from 5.5°C to 8°C. At this time, the liquid temperature in the liquid reservoir will be higher than the saturation temperature corresponding to the changed condensation pressure, and evaporation will occur at this time, and the evaporation will not end until the liquid temperature drops below the saturation temperature again.
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Disassemble the device shell

First disassemble the casing of the unit. Of course, it is not necessary to disassemble all the casings. We only disassemble the parts and find the refrigerant filling port. If the filling port is on the equipment casing (obviously you can see it) Place), there is no need to disassemble the unit shell.
How to add refrigerant to small central air conditioner

Check the pressure gauge and connect the pipe

Check whether the R410 refrigerant tube is reset to zero, check whether there is a crack or aging phenomenon in the refrigerant filling pipe, and replace it immediately if any problem is found. Connect the yellow tube in the middle of the pressure gauge to the refrigerant bottle, close the valve corresponding to the red tube on the right side of the pressure gauge, and open the valve of the blue tube on the left.
How to add refrigerant to small central air conditioner
How to add refrigerant to small central air conditioner

Air exhaust parallel pipe

Open the valve on the refrigerant bottle a little bit and feel a little cool air coming out of the blue tube, indicating that the air in the tube has been drained, and connect the blue tube to the refrigerant filling port. At this time, it is best to cooperate with two hands, one hand holding the blue tube close to the nut, and the other hand twisting the connecting nut on the tube.
How to add refrigerant to small central air conditioner

Refill refrigerant

After all the above work is done, the refrigerant can be filled. Open the valve on the refrigerant tank to the maximum, start the unit and observe the pressure change of the pressure gauge.
How to add refrigerant to small central air conditioner

Dismantle

When the pressure on the pressure gauge is consistent with the pressure on the low pressure side indicated in the manual, it means that the filling volume is enough. At this time, first close the valve on the refrigerant tank, then close the valve on the blue tube, and finally remove the connection with both hands. Screw on the blue tube on the filler port.
How to add refrigerant to small central air conditioner

Restore

Install all the disassembled unit shells. Remove the yellow tube connected to the refrigerant tank, pack up the tools, and complete the filling.