The so-called fogging means that after the headlights are turned off and cooled down, a thin layer of water vapor adheres to the inner wall of the lampshade. We know that headlights generate heat when used. To ensure normal use of headlights, heat must be dissipated, just like the engine needs to be cooled. Therefore, there is a pressure relief valve for heat exchange at the rear of the headlight. After the headlight is heated up during use, the internal pressure rises, and the external air temperature is low and the pressure is small. Therefore, the flow and exchange of air can be carried out through the pressure relief valve to achieve heat exchange. However, the outside air contains water vapor, so when humid air enters the headlights, fogging may occur when the headlights are turned off for cooling. In this case, the water vapor can dissipate on its own, which is normal.
The headlights are foggy (picture from the Internet)
Characteristics of fog (pictures from the Internet)
Another situation is water intrusion. We know that if water enters the headlight, it usually enters from the top of the headlight and then flows under the headlight. This will form obvious traces of water flow, similar to a waterfall. Even if the water is dry, There will also be some traces, just like there are traces on the path a snail passes,
Characteristics of water ingress (pictures from the Internet)
The cause of water intrusion is simply poor sealing. The reasons for poor sealing should be considered from these aspects. First, the headlights are aging and the lamp shells are cracked. Some tiny cracks cannot be seen. The second is whether the waterproof cover behind the headlight is sealed properly. If there are any cracks, just use glue to seal them. The third is that the sealant is not sealed well. In this case, it needs to be resealed. If you can't fix it yourself, you can go to a lamp modification shop. Note: Water intrusion is a quality problem, and the assembly can be replaced with a new one during the warranty period.
pay attention:
Accidents resulting in death mostly occur at night, and there are many accidents caused by problems with the brightness of car lights. If there is water in the headlights, it will affect the light transmittance, especially at night, which will greatly reduce the vision. It will also change the direction of the headlights, affecting other vehicles and pedestrians, and seriously disrupting the driver's normal vision. If water accumulation is severe, light bulbs and circuits may be damaged.
If there is too much water inside the headlights, you should go to a 4S shop for disassembly and repair as soon as possible. Then you need to disassemble the headlight and open the lampshade. After drying, check whether there is any damage or possible leakage on the surface of the headlight. If no abnormality is found, you need to replace the headlight back cover sealing strip, vent pipe and other hardware equipment. If the water accumulation is severe, the headlight assembly needs to be replaced.
