[Northern SRX]

Originally Posted by crystal_red

That's not correct; the 'vent' is there to allow heat from the light only to escape. There should be no communication whatsoever between the whole assembly and the outside environment. See below...

All about headlight repair, restoration and cleaning

Now, beside the fact that worn or cloudy headlights need to be either replaced or restored as they are a major night time driving issue, there are a few other items to look at or that you may notice need fixing. On older cars and badly worn headlights there may be water inside the lens. In some cases it can be so bad the lens looks like a fish bowl – full of water. This can also happen on brand new lenses from a bump or similar as the seal around the lens may have become compromised and will let moisture in (evidence of this is condensation inside the lens). Condensation in the headlights due to hairline cracks and bad seals is much more common in newer vehicles. If there is water or condensation inside it must first be removed before any other repairs can be effective. This is accomplished by using a small drill bit and drilling a small hole in the bottom of the headlight assembly. It is easiest to remove the lens first and make sure the hole goes all the way into the headlight chamber. Do this in the grey headlight assembly, not the frontal clear plastic so the hole will later be hidden. A key tip is to wrap the drill bit with tape to the desired depth so you don’t protrude too far into the lens or make too big of a hole.

Allow the water and condensation to completely drain over a few days. It is a good idea to place the headlight assembly next to either a dehumidifier or air conditioner vent or duct as that will further remove and extract moisture from the headlight. Reseal the hole with silicone seal (at all automotive stores – do not use super glue or other glues as they will will crack and leak and then you will have the same problem all over again). It’s also a good idea to check the whole seal that attaches the outer globe to the headlight assembly – remember, if it looks iffy then coat and reseal it(especially on Ford, GM and Dodge headlights as these tend to leak very early - reseal it if necessary). Then reinstall.

Great post - thanks.