How to distinguish the quality of the expansion valve of the automobile air conditioner:
When refrigerant is added to the air conditioner, due to poor vacuuming or moisture in the refrigerant, the inner copper tube or aluminum is oxidized. After a long time, the oxidation phenomenon will increase and the pipeline will be blocked. The solution is to turn on the air conditioner, heat the condenser, and return most of the refrigerant to the evaporator;
After shutting down, use a vacuum pump to filter the pump to recover the refrigerant; disassemble the two pipes at the evaporator, use a high-power blower to heat the evaporator, pipes, expansion valve, and filter, so that the water vapor is naturally discharged, and then use Use nitrogen to remove the water in the evaporator and pipeline; close the pipeline, add nitrogen to the system to 10kg/cm2, and keep the pressure for more than 2 hours. If the pressure does not decrease significantly, the system can be evacuated to minus 0.1mp, and the compressor can be added to lubricate the oil and refrigerant according to the specified specifications. Start the air conditioner, check the working pressure of the evaporator and condenser, and check the pipeline for leaks. If there are no exceptions, the job is done.