The fogging inside the car headlights is usually a normal phenomenon caused by temperature difference, not a quality problem. The inside of the headlight is not vacuum, but sealed, but not completely vacuumed.
During use, the headlights will generate heat, so ventilation holes will be left to remove excess heat and keep the headlights in a stable environment. These ventilation holes allow water vapor in the air to enter the interior of the lamp. When the temperature difference between the inside and outside is large, the water vapor will condense on the inner surface of the lampshade to form fog. This situation is particularly obvious in winter or after washing the car, because the sudden change in outside temperature will cause the temperature difference between the inside and outside, which will cause the water vapor to condense. Generally, these fogs will gradually dissipate with the use of the headlights, and no vacuum treatment is required.
If the fog is heavy and does not dissipate for a long time, it may mean that the sealing performance of the headlight is poor, and professional repair or replacement may be required. But in most cases, the appearance of fog is normal, especially after washing the car in summer or when the temperature changes in winter. Therefore, car owners do not have to worry too much about the fogging of headlights. Unless the fog is too heavy and does not dissipate for a long time, vacuum treatment is not required.
