How to check for refrigerant leakage and maintain the refrigeration function of air conditioning system_maintenance

The air-conditioning system has gradually become the standard equipment of cars. There are many types of air conditioners used in existing automobiles, and their structures are similar. The maintenance interval should generally be once a year or as needed. In use, if it is found that the cooling effect is not good, it should be checked. The failure is generally caused by refrigerant leakage. You can check and repair through the following steps.

1. Find the leak site

Currently, the air-conditioning system used on the vehicle is generally a single-cooling open type, and the refrigerant mostly uses Freon (R12 or Freon's substitute product 134a). In use, the refrigerant is easy to leak from the connection joints and the oil seal, and the leakage of the refrigerant will cause the phenomenon of poor cooling effect or no cooling.

(1) Check for traces of oil leakage. In the air conditioning refrigeration cycle system, cooling oil is used to lubricate the sealed bearings and other moving parts in the compressor. A small amount of lubricating oil will enter the refrigeration cycle system together with the refrigerant. If the refrigeration cycle system leaks, oil stains will appear at the leak. Therefore, if oil stains are found in the pipeline and joints during the inspection, it can be determined that there is a leakage failure and repairs should be made.

(2) Observe the inspection window to determine the refrigerant leakage. Start the engine (about 1000r/min), turn on the refrigeration control switch (A/C), place the temperature switch lever at the COLD (cold) position, and open the fan switch to the z* position, and the refrigeration can be observed from the inspection window The flow state of the refrigerant is used to determine whether there is leakage in the refrigeration cycle system.

The flow of the refrigerant is normal: the refrigerant is generally transparent, and the air at the air outlet is cold at this time. The state of the refrigeration system is normal.

Insufficient refrigerant: When the refrigerant is insufficient, the flow of bubbles will often be seen, the refrigerant is milky white, and the cooling effect is not good at this time.

No refrigerant: If the refrigeration system leaks seriously, nothing can be seen in the observation glass window, and the air conditioning system will not be cooled at this time. There are two inspection windows A and B on the liquid storage tank of the Fukang car. The inspection window A can determine whether the moisture content of the desiccant in the liquid storage tank is saturated. If it is blue, it means normal; if it is red, it means that the water is saturated. The refrigerant in the air conditioning system should be drained slowly, the desiccant in the liquid storage tank should be replaced, and then the refrigerant should be refilled. The function of the B inspection window is the same as the content introduced above, and it is mainly used to observe the refrigerant.

During the inspection, if oil stains are found on all connections or on the surface of the condenser, it generally indicates that there is a refrigerant leak. When a leakage is found, the leakage fault should be eliminated in time, and the refrigerant and lubricating oil should be added to prevent the lubricating oil from leaking and damaging the air-conditioning system.

2. Check the working condition of the air-conditioning system

During the inspection, park the car on a well-ventilated place, keep the engine at a medium speed, and turn on the air conditioner to the z* block Circulate the air in the car.

(1) Judge the air conditioner status from the temperature of each part. Touch the air conditioning system and its components with your hands to check the surface temperature. Under normal circumstances, the low-pressure pipeline is in a low temperature state, and the high-pressure pipeline is in a high temperature state.

High pressure pipeline: the inlet of the expansion valve of the condenser of the compressor outlet. These parts should be warmed first and then hot. Be especially careful when touching them to avoid burns. If a particularly hot spot is found at one of these points, it means that there is a problem and the heat dissipation is not good. If a point is particularly cold or frosty, it also indicates that there is a problem here, and there may be a blockage. If there is a significant temperature difference between the inlet and outlet of the dry reservoir, it indicates that there is a blockage here.

Low pressure pipeline: Expansion valve outlet evaporator compressor inlet, these surfaces should be from cold to cold, but frost should not occur at the expansion valve.

There should be a significant temperature difference between the high and low sides of the compressor. If there is no significant temperature difference, it means that there is no refrigerant in the air conditioning system and the system has obvious leakage.

(2) Clean up the debris on the air conditioner. Check the evaporator channel and the surface of the condenser, as well as whether there is any debris or sludge between the condenser and the engine water tank (stop inspection). Pay attention to cleaning and clean it carefully. The condenser can be gently scrubbed with a brush, and be careful not to use steam to flush it.

(3) Check and adjust the air conditioner belt. Check whether the belt tightness is appropriate and the surface is intact (the same as the engine belt check and adjustment). If abnormalities are found in the above inspection, repairs should be made.