I can definitely tell you that the small water tank that blows the warm air is too dirty and blocked. At low speed, the water pump speed is low and the water flows slowly and it is difficult to flow through the small water tank. At high speed, the water can be flushed when the speed increases. In the past, it became hot. Find a water tank repair place and let their car wash water gun rinse the small water tank. If it still doesn't work, then you have to replace it with a new one! My car has the same reason!