Why is it said that air conditioning water corrodes car paint?

[Shawn]

Air conditioning water is the moisture condensed from the air by the evaporator. It is pure water and non-corrosive, having no effect on car paint. Specific reasons for the increase in car air conditioning water: Because the car cooling system is located inside the dashboard, equipped with an evaporator: when the air conditioning is turned on, the surface temperature of the evaporator is very low, and the moisture in the hot air inside the car will condense on the heat-absorbing fins of the evaporator. The plastic housing of the evaporator collects the water droplets and drains them out of the car through pipes. If the vehicle stops and restarts after a period of driving, a pool of very clean and transparent water can be seen on the ground under the car, which is the water discharged by the car air conditioning. When using car air conditioning in summer: sometimes the compressor located in the engine compartment (low-pressure area) can also condense moisture from the air, dripping onto the ground (sometimes the amount of water is even greater than the drainage from the evaporator). If the low-pressure pipes of the car air conditioning are not wrapped with insulating foam: the surface of the pipes can easily condense moisture from the air, and water droplets will also condense and accumulate at the lowest point of the pipes, dripping down.