Refrigerant Leak Detection And Causes
A Refrigerant leak is a common fault in air conditioning. Refrigerant leakage can easily cause environmental pollution and increase vehicle owners’ costs and time to maintain their vehicles.
Here are seven easy ways to detect refrigerant leaks, along with their pros and cons
1. Visual leak detection
Visual refrigerant leak detection is simple and cost-effective but comes with significant limitations. Unless there is a sudden system rupture with a large leakage point and the system is leaking a colored liquid medium, visual detection cannot pinpoint the leak, which is because leaks typically occur in very small areas that are hard to spot, especially considering that many parts of car air conditioning systems are nearly invisible.
2. Soap water leak detection
Inject nitrogen gas into the system at a pressure of 10-20kg/cm², then apply soapy water to different parts of the system; the bubbles indicate the leaking spots. This method is commonly used in roadside repair shops, but human arms have limitations, and so does human vision, often resulting in an inability to spot the leak points.
3. Nitrogen water leak detection
Fill the system with 10-20kg/cm2 pressure nitrogen and immerse the system in water. The bubbling point is the leakage point. This method is identical to the previous soapy water leak detection method. Although the cost is low, it has obvious shortcomings: the moisture used for leak detection can easily enter the system, causing the materials in the system to corrode. At the same time, the high-pressure gas may also cause more damage to the system. If the damage is large, the labor intensity during leak detection will also be very high, increasing the cost of maintenance and repair.
4. Halogen lamp leak detection
Ignite the refrigerant leak detection lamp and hold the air tube on the halogen lamp. When the tube mouth is close to the leakage point in the system, the flame color changes to purple-blue, indicating a large amount of leakage here. This method produces an open flame, which is dangerous, but combining the open flame and the refrigerant will produce harmful gases. In addition, it is difficult to locate the leak point accurately. So, almost no one uses this method now. If you can see it, you are in the stage of uncivilized society.
5. Gas differential pressure leak detection
Utilize the air pressure difference inside and outside the system, amplify the pressure difference through the sensor, and express the leak detection results in the form of numbers, sounds, or electronic signals. This method can only “qualitatively” know whether the system leaks but cannot accurately find the leak point.
6. Electronic leak detection
Move the probe towards the possible leakage area. When the refrigerant leak detection device sounds an alarm, it indicates much leakage. Electronic leak detection products are easily damaged, complex to maintain, easily affected by environmental chemicals such as gasoline and exhaust gas, and cannot accurately locate leak points.
7. Fluorescence leak detection
It uses the principle that fluorescent leak detectors emit bright yellow-green light under the irradiation of ultraviolet/blue light leak detection lamps to detect fluid leakage in various systems. When using it, you only need to add the fluorescent agent into the system in a certain proportion.
After the system operates for 20 minutes, wear special glasses and illuminate the outside of the system with a leak detection lamp. The leakage point will fluoresce yellow. The advantages of fluorescent leak detection are accurate positioning, the leakage point can be directly seen with the eyes, and it is simple to use, easy to carry, and has low maintenance cost. It represents the development direction of automobile refrigerant leak detection.
9 common places where air conditioner refrigerant leaks
The air conditioner refrigeration system comprises a compressor, condenser, four-way reversing valve, throttle, and evaporator. Refrigerant leak points in the refrigeration system usually occur in these parts.
1. Evaporator leakage
There are many welding joints on the left and right sides of the evaporator, and there are also many possible leakage points. The main reason for the leakage of the newly installed air conditioner is that the employees of the air conditioner manufacturer have poor welding skills. They put the welding rod at the welding joint without burning the copper pipe red (the temperature did not reach 600℃~700℃). The solder failed to fuse, resulting in welding joints that were pinched, scummy, and not smooth.
For a newly installed air conditioner, after opening the outdoor unit stop valve and discharging the air from the indoor unit, the sound of indoor unit evaporator leakage can sometimes be heard with the ears. It can be seen that the air conditioner is leaking, and the evaporator solder joints cannot be ignored.
2. Leakage at the indoor unit connection
The refrigeration system is faulty if the air conditioner operates normally but no cold air is blown out from the indoor unit. If you find oil stains at the connection of the indoor unit, it means there is a refrigerant leak here.
First, use two wrenches to tighten the “nazi” at the connection, then use detergent to rub out the foam and apply it, and check whether bubbles are blowing out of the connection. If not, add R22 gas refrigerant from the low-pressure gas valve bypass, subject to low pressure 0.5MPa. Stop the machine and use detergent to check the connection point again. After 3 to 5 minutes, there are still no bubbles, indicating that the air leakage problem at the connection has been eliminated.
3. The outdoor unit stop valve core leaks
The outdoor unit stop valve core leakage mostly occurs after the unit is moved. Due to the back-and-forth rotation of the switch valve shaft in and out and the aging of the rubber ring, the outer sealing rubber ring of the shaft is worn out, causing the stop valve to leak. Use detergent to detect leaks, you can find a small bubble coming out in about 3 minutes.
Small leaks can be eliminated by adding an asbestos round gasket to the secondary sealing cap. If the leakage is serious and a “hissing” sound can be heard, the refrigerant can be drained from the low-pressure gas lock nut of the outdoor unit. When draining, there should be 0.1MPa pressure of refrigerant left in the pipe to prevent air from entering the system and causing vacuuming trouble.
4. Leakage in the U-shaped pipe of the outdoor compressor
Leakage in the U-shaped exhaust pipe of outdoor compressors is common. The main reason is that the copper pipe has a thin wall and poor material. After being bent into a U-shape, small cracks appear. The vibration generated by the compressor during artistry increases the cracks. Most of this kind of leakage failure will cause the gas to leak out, and it will be discovered after inspection when there is no cold air blowing out from the indoor unit.
5. The capillary tube of the outdoor unit is vibrating and leaking
The air conditioner is not cooling, and the refrigerant leaks may also be because the vibration generated by the compressor when working causes resonance friction between the two tubes, which wears the tube wall and causes the refrigerant to leak out.
6. Low-pressure bypass valve core leaks
The refrigeration system of split air conditioners is replenished with refrigerant (known as “fluoridation”), which must be filled from the low-pressure bypass. Use the gas-filling pipe with a thimble to push open the low-pressure gas-filling valve stem. The R22 refrigerant gas in the refrigerant cylinder and the refrigerant gas in the air conditioner are connected, and then filling can be performed.
The reason for the leakage of the valve core is that the thimble of the gas filling pipe is adjusted too long, and the thimble of the bypass air valve cannot rebound after being pushed in, so the valve core cannot be reset. The troubleshooting method is to insert the key of the special air conditioner into the gas filling valve core, give the valve core a force, and make the valve core spring pop up so that the valve core leakage fault can be eliminated.
7. Compressor terminal leakage
According to experience, compressor terminal leakage accounts for more than 2% of leakage faults. Remove the outer cover of the overcurrent and overheating protector. If you see oil stains around the compressor terminal, it means there is a leak.
8. The pipeline is flat and leaking
Flattened and leaking pipes often appear after home renovations. Some decoration workers do not understand that there is refrigerant in the refrigeration pipes. If they bend them casually, it will not be easy to find the deflation due to the insulation cover outside the pipes. After the pipe became dented, the refrigerant leaked out, and when the machine was turned on again to add fluorine, the refrigeration system experienced two shut-off symptoms.
9. Four-way reversing valve leaks
There is a lot of leakage at the corners of the three copper pipes under the four-way valve of the heating and cooling air conditioner. If there are oil stains at the corners, there is a leak.
Common causes of air conditioner refrigerant leak
1. Unreasonable design of air conditioning and refrigeration system
The air conditioning and refrigeration system comprises a compressor, condenser, expansion valve and evaporator. If the design of these components is not reasonable, it is easy to cause refrigerant leakage. Poor compressor sealing, aging evaporator pipelines, expansion valve failure, etc., can all cause refrigerant fluid leakage.
2. Improper use of air conditioners
Improper use of air conditioners is also an important cause of refrigerant fluid leakage. Long-term operation of the air conditioner, frequent switching on and off, and sudden power outages during use will cause damage to the refrigeration system and lead to leakage of refrigerant fluid.
3. Improper air conditioning maintenance
Air conditioner maintenance is also one of the causes of refrigerant fluid leakage. When disassembling the air conditioner, not paying attention to the protection of the refrigeration pipelines or using unqualified maintenance tools will cause damage to the refrigeration system, resulting in refrigeration fluid leakage.
4. Refrigeration pipeline aging
After the air conditioner has been used for a long time, the refrigerant pipes in the pipes and the rubber seals connecting the pipes are easily affected by oxidation and aging, and air leakage is prone to occur.
5. The pipeline connection is not firm
When the air conditioner is running, the refrigerant in the pipeline will be under a certain pressure. If the connection is not firm, it will cause refrigerant leak.
6. Refrigeration pipeline wear
When the air conditioner is running, the refrigerant in the refrigeration pipeline will flow through the pipeline, and long-term wear and tear will also cause refrigerant leak.
7. Refrigeration pipeline extrusion
When installing or repairing air conditioners, if the refrigeration pipeline is squeezed or collided, it will also cause refrigerant leak.
8. The refrigeration pipeline is blocked
If there are debris or ice cubes and other substances in the refrigeration pipeline, the refrigerant will not flow smoothly, and the pressure will increase, resulting in refrigerant leak.
Common air conditioning refrigerant fluid leakage treatment method
1. Find and eliminate leak points in time
If air conditioner refrigerant fluid leakage is found, the refrigerant leak point must be found in time and eliminated. Leak points can be determined by using a leak detection instrument. After finding the leak point, you can use welding, seal replacement and other methods to eliminate it.
2. Replenish refrigerant liquid
If the leakage of refrigerant is small, it can be replenished according to the type of refrigerant of the air conditioner. However, it should be noted that when replenishing the refrigerant liquid, you must choose the same type as the original refrigerant. Otherwise, it will affect the performance of the air conditioner.
3. Replace refrigeration system components
If there is a lot of refrigerant leak, or the refrigerant leak point is on a component of the refrigeration system, the corresponding component needs to be replaced. If the compressor seal is poor, the compressor needs to be replaced; if the evaporator pipeline is aged, the evaporator pipeline must be replaced, etc.
4. Prevent refrigerant leak
It is also very important to prevent refrigerant leak. First, you must use a regular brand of air conditioner and use and maintain it according to the instruction manual; secondly, you must perform regular maintenance and repairs on the air conditioner to avoid damage to the refrigeration system caused by long-term operation or failure.
The leakage of air conditioner refrigerant fluid will not only affect the performance of the air conditioner but also cause harm to human health. Therefore, we must master dealing with air conditioning refrigerant leak problems. When using air conditioners, pay attention to care and maintenance to avoid damage to the refrigeration system due to improper use or repair. If there is a refrigerant leak problem, the leakage point must be found in time and eliminated to ensure the normal use of the air conditioner.
5. Check the refrigeration pipeline
First, check whether the refrigeration pipeline is damaged, aged, or loosely connected. If necessary, replace or repair it in time.
6. Add refrigerant
If the air conditioner refrigerant leaks, you need to add refrigerant, but when adding refrigerant, you need to pay attention to the type and amount of refrigerant. Otherwise, the cooling effect of the air conditioner will be affected.
7. Clean the pipelines
If debris or ice cubes are in the refrigeration pipeline, the pipeline must be cleaned to ensure a smooth refrigerant flow.
8. Replace the sealing ring
If the air conditioner refrigerant fluid leakage is caused by aging or damage to the sealing ring, the sealing ring needs to be replaced in time.
In short, air conditioner refrigerant fluid leakage is a relatively common fault and needs to be dealt with in time to ensure the normal use of the air conditioner. When using air conditioners daily, you should also pay attention to the care and maintenance of air conditioners to reduce the occurrence of malfunctions.