An air conditioning refrigeration system is composed of a compressor, condenser, throttling valve, evaporator, and connecting copper pipe and many other parts and accessories. The point of refrigerant leakage may appear in any part of the refrigeration system.



the air conditioner added with refrigerant is cooling the room

Figure 1: The air conditioner is cooling the room.

Evaporator Leaking

There are many welded junctions on the left and right sides of the evaporator, so are leaking points. The newly installed air conditioner leaking is most probably because of the wrong welding in the factory.

When the temperature of the copper tube has not reached 600 ℃ ~ 700 ℃, the welding rod is placed at the welding joint, causing the copper tube not to be fused with the solder. As a result, there is pinch welding, slag, and non-smooth welding joint, leading to the leakage of refrigerant.

Solution
Remove the electrical box on the right side of the indoor unit, as well as the pipe and splint fixed at the back of the evaporator and its left and right positioning screws. After you pull out the evaporator for 5cm, rotate the evaporator 90 degrees with both hands and pull it out along the pipe. After removing the evaporator, you should put it in a flat and clean place and wipe the oil stains on the leakage point with a dry cloth. The leakage point shall be welded by silver welding.

Indoor Unit Leaking

The air conditioner operates normally, but there is no cold air blowing out from the indoor unit. First, check whether the refrigeration system is normal. If you find the oil stain at the connection of the indoor unit, it indicates that there is refrigerant leakage.

Solution
You can apply with foam to examine whether bubbles are blowing out at the joint. If not, the refrigerant can be added to the bypass hole of the low-pressure gas valve, with a low pressure of 0.5MPa. When the air conditioner stops, check if there are bubbles. After 3 to 5 minutes, if no bubble is found, the air leakage at the connection is eliminated.



cartoon of the air conditioner running

Figure 2: Cartoon of an indoor unit of air conditioner

Throttling Valve Leaking of Outdoor Unit

After the unit is moved, the throttling valve core of the outdoor unit may leak. Due to the frequent operation of the valve shaft and the aging of the rubber ring, the sealing rubber ring outside the shaft wears, resulting in the leakage of the throttling valve. If you find the leakage serious and hear the noise sound, you should discharge the refrigerant from the low-pressure gas lock nut of the outdoor unit.

Solution
Screw out the screw of the stop valve with an internal hexagon wrench, block the air leakage with the left hand, coil 4 circles of raw material belt with the right hand at the screw buckle and sealing ring of the screw, and quickly screw into the screw of the stop valve and install the snap ring.

Then you can wind 2-3 circles of raw material belt on the secondary sealing screw thread and put on the secondary sealing cap. It is better to add F22 refrigerant from the filling place of low-pressure gas stop bypass valve, and add F22 gas to about 0.5MPa (for reference).

U-Bend Exhaust Pipe Leaking of Compressor

The leakage of the U-bend exhaust pipe of the compressor in outdoor unit is common. The reason for the leakage is the thin copper pipe wall and the poor material. After bending into a U-shape, there will be small cracks, and the vibration generated by the compressor increases the cracks, which will leak out the refrigerant.

Capillary Vibration and Leaking of Outdoor Unit

The vibration produced by the compressor when it works, which causes resonance friction between the two pipes and causes the pipe wall to wear and leak to leak the refrigerant.

Solution
Saw the 6mm copper tube and wrap the capillary leak, and then weld it with silver. In addition, it’s feasible to replace the capillary with the same inner diameter and specification. Before welding, clear up inflammable and explosive materials within 1.5m around. Please cover the back of the capillary with an iron plate.

You should control the fire, and welding over medium heat is better. When it reaches about 600 ℃, you should put the silver electrode into the welding joint quickly. After the solder and the copper tube melt together, you could quickly take away the torch, otherwise, the capillary tube will be burnt out.

Leaking of Low-Pressure Bypass Valve Core

The refrigerant (commonly known as "fluorine") in the air conditioning system must be filled from the low pressure bypass. Use the gas filling pipe with thimble to open the low-pressure gas filling valve rod, and connect the R22 refrigerant gas of the refrigerant cylinder with the refrigerant gas of the air conditioner. If the ejector pin of the gas filling pipe is extremely long, the ejector pin of the side ventilation valve cannot spring back after being pushed in and the valve core cannot be reset.

Solution
You should insert the special key into the filling valve core, give a force to the valve core and make the valve core spring pop up, then the valve core will stop leaking.

Compressor Terminal Leaking

Compressor terminal leakage accounts for more than 2% of the leakage fault. After removing the over-current heat protector cover, if you see oil around the compressor terminal, it means there is a leakage point.

Solution
Prepare with C31 double tube adhesive in the ratio of 1:1 and apply it to the wiring. Because the refrigeration system is in a vacuum state, the C31 glue penetrates the leakage point. After the leakage point is coated with glue, bake a 100W light bulb at the adhesive point for 30 minutes to make the glue more easily penetrate the leakage point.

Pay attention to the distance between the bulb and the C31 glue and 20cm is better. Otherwise, the glue will be baked, which will reduce the plugging effect. You can check if the compressor terminal is leaking after 2 hours of gluing. Finally, evacuate the machine and test it by adding fluorine to restore refrigeration.

Pipeline Leaking

The pipeline leakage occurs mostly after the decoration of the house. The pipeline has been bent during the decoration work, causing the refrigerant to leak out. Because of the insulation sleeve outside the pipeline, it is not easy to find the pipeline bending. Even if the fluorine is added again, there will be closure symptoms in the refrigeration system.

Solution
Remove the concave section with a cutter and weld it with a sleeve. After re-pressing, checking if there is leaking, evacuation, adding fluorine, you can start the machine with the remote control.

Four-Way Reversing Valve Leaking

At the angle of the three copper pipes under the four-way valve of the air conditioner, there probably is leaking. If you find oil stains at the angle, there should be a leakage point.

Solution
First, discharge the refrigerant and wrap the four-way reversing valve with a wet towel. When welding, you should aim at the leakage point. When it reaches the welding temperature, quickly weld it with silver.

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