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Judgment Method for Refrigerant System Leakage of LG Air Conditioners - Maintenance Summary

There are many reasons for the deterioration of air conditioner's cooling (heating) effect, such as abnormal voltage, which may cause protective shutdown during operation; compressor cylinder jamming, shaft drawing or motor winding burnout, although the outdoor fan is running, but the compressor is not working; poor contact or damage of the running capacitor, power break of the fan motor or damage to the fan motor, leading to the failure of the fan to rotate; clogged air filter net and poor ventilation, resulting in the inability of cold (hot) air to circulate effectively; damaged four-way electromagnetic valve, leading to high and low pressure mixing, affecting the cooling (heating) effect; blocked capillary tube or dry filter, reducing the amount of refrigerant flowing into the evaporator, causing poor cooling (heating) effect. None of the above faults are caused by a reduction in refrigerant, but the fault symptoms caused by refrigerant leakage are basically similar. The methods for determining whether the air conditioner lacks refrigerant are as follows:

(1) Check the temperature and dew formation of the liquid supply pipe and return gas pipe. Run the air conditioner in the cooling mode for 20 minutes. If there is condensation on the return gas valve and return gas pipe of the outdoor unit, and the temperature of the return gas pipe is significantly lower than that of the liquid supply pipe when touched by hand, it indicates that the system has sufficient refrigerant and the air conditioner is running normally. Any of the following conditions indicate insufficient refrigerant: ① Liquid supply pipe is dewed, but the return gas pipe is not dewed; ② Liquid supply pipe is frosted; ③ Liquid supply pipe is slightly cool without dew, and the return gas pipe is not cool; ④ Both the liquid supply pipe and the gas addition pipe are not cool.

(2) Measure the pressure at the return gas valve. Connect the pressure gauge to the low-pressure angle valve liquid inlet of the air conditioner and measure the low-pressure pressure during operation. Normally, when the ambient temperature is around 30℃, the low-pressure pressure during cooling operation should be 0.45~0.55Mpa, and for heat pump type air conditioners during heating operation, it should be 1.8Mpa. If the pressure is below these values, it indicates insufficient refrigerant. The lower the pressure, the greater the leakage. If there is basically no pressure, it indicates that the refrigerant has leaked completely.

(3) Pressurize with nitrogen gas (inject 1.5Mpa nitrogen gas), observe the four joints of the two connecting pipes, the valve stem of the gas-liquid valve, and the liquid inlet port for any oil stains. The presence of oil stains indicates leakage.

(4) Use a detector to find the general area of leakage, then apply soapy water. If bubbles appear, it is the leak point.

(5) For heat pump type air conditioners, the leak detection of the indoor unit and connection pipe parts should be carried out under heating operation state because the inspected part is under high pressure at this time, making it easier to find the leak point.

Source: http://blog.sina.com.cn/lgkongtiaowx