Many drivers have experienced the frustration of seeing their vehicle’s headlights fog with condensation. Not only can the moisture diminish the light your headlights provide, but it can also corrode your assembly over time. So, why have your headlights started fogging up? And what can you do about it?
What causes car headlights to fill with water?
Headlights generate heat when in use. They need proper ventilation to prevent condensation from gathering within the unit, especially when the vehicle isn’t in use. If the outer lens cools down faster than the air inside the headlight unit, condensation can form. This is why you may see fog in your headlights first thing in the morning after parking your car overnight.
Most headlight housings have vents at the bottom and top to manage the difference in pressure. Otherwise, the unit will eventually crack and break down. The culprit could be bad headlight seals or a crack in the headlight’s housing. Either scenario would allow moisture to seep into the assembly and cause fogging and possibly other issues.
Some vehicles have headlight units that don’t vent well. Another contributing factor could be where your car is parked. If it’s kept in cool underground parking structures or damp, shady areas, this can cause the condensation.
What can be done the condensation?
Starting the car and turning on the headlights can create enough heat to evaporate the moisture. As the day continues and temperatures rise, the condensation may dry up. Going for a drive can clear it up; this allows air to flow through the vents in the unit, the same way as a defroster dries your windshield.
Checking the unit vents for blockages is a good idea if your headlights are fogging. Make sure the vents are clear of debris, insects, and any other matter that could block the airflow. Some people even blow canned, compressed air through the vents to clean them thoroughly.
If there appears to be quite a lot of water in your headlight assembly, try removing the housing and drying it manually. Dump out the water and wipe the housing with standard rubbing alcohol. Clean it, and repeat the process. Allow everything to dry in the sun or in a warm area. Check the vents to make sure they are clean and clear.
