Moisture inside the headlight

So now the air inside the headlights is warm. If you turn your lights off or pull your vehicle into the shade, there will be a large temperature difference between outside and inside the lens. The cool air wants inside and it begins to sneak into the tiny vents that are found on most headlights. When that cool air meets with the warm, condensation is formed. That happens on the warm side of the lens, so you have got a little layer of moisture on the inside of the headlight lens.

But almost every headlight has a vent tube. This allows large amounts of heat to exhaust. If you turn the lights on or pull your vehicle back into the sun, the moisture will eventually evaporate through the vent tube.

There is another reason that your headlights could be filled with condensation. The bulb socket boots may not be seated properly. When the headlights are on and hot, that heat will pull moisture in through those tiny spaces where the boot isn’t sealed right. Thus, to fix this problem, you just remove the bulb and the seat and then install it correctly. If the boots are broken, you need to buy a new one to replace it.

If you’re seeing a lot of water inside your headlights, it means the seal around your bulbs or headlights isn’t working properly. There could be rain water dripping into your headlights. Or you wash your vehicle with an inappropriate way, causing water to flow into the inside of the headlights. You will have to remove the bulbs and check the seal around them. Sometimes, when replacing your headlights with new ones, those seals fall off or just don’t seal back like they should do. Get some new ones and your headlights will stop taking on water.