Condensation in headlight

[Jarre]

Hey guys,

I went through a car wash earlier and when i got home i saw a tonne of condensation! I've ran my lights and had a hair dryer on it too, that got rid of it but then 5 mins later its starting to come back again, from the indicator end of the headlight.

Now i checked the covers on the back and the sidelight/main beam cover wasn't quite on properly, so i assume that's where it has come from, it's now back on properly but i'm confused as to why when ALL condensation was gone, it is now coming back again.

 

[andycupra]

ok..
temperature changes the ability for air to hold moisture.
The warner the air the more moisture it can hold, and vice versa

So when you heat the air with a hairdryer for example you increase the temperature of the air, encourage evaporation and so it clears.
however when the air cools the condensation will reappear as you have effectively sealed in warm humid air which looses its ability to hold moisture as the temperature drops.
This is also why we get condensation on windows, especially in the winter as the air is humid inside the car (often due to people wearing coats) but also the air cannot hold so much moisture. then, added to this the glass is cold, so when the air is cooled by the glass you get condensation.

When people wash cars, they often cool the lense and so if the moisture in the headlight is at a reasonable level then the cool lense lowers air temp and voila. (also if there are any small entry points water ingress is possible).

There are a few cures to condenation:
dehumidification
heating the glass/lense.. (thus steam free mirrors)
air circulation... (as per bathrooms with extrator fans)

Headlight units have issues, as they are effectly poorly sealed sealed units. What i mean is, if you put dehumidified air in them and sealed them 100% then great! - one problem, not many are 100% sealed, and you wouldnt be happy paying out for a whole new headlight everytime a bulb goes... so they end up being excessible / not sealed properly. I am also sure they dont go to the trouble of dehumidification.
The other option is to have good air circulation.. (air changes) but again there is a downside as the headlight is open to the elements...

Hedlights end up being neither sealed nor open. (but closer to being a sealed unit that anything else.

So what to do...
In your case, use the hair dryer as you did before.. but then finish it off by blowing some cold hair through, then leave the cover off for a good period so that humid air is removed. doing this on a day when the temperature and humidity is lower would be preferable.
You can then re-seal the unit, but there are no guarantees...
Some have increased air circulation by drilling holes in the rear of the headlight unit and fitting pipework or covers to prevent water imgress... but id not recommend this at this stage.

 

[Jarre]

hmm, so how can i remove the condensation properly? Maybe heat with a hair dryer but open the covers on the dipped and main beam so the air can escape?

 

[rik_t]

Leave covers off during warm day. Soon sort it.

 

[Jarre]

Leave covers off during warm day. Soon sort it.

no chance of sorting that for another 10 months then!

 

[andycupra]

no, a cold day with low humidity is preferable, see my expanded first reply

 

[Jarre]

that is expanded!! Tomorrow if the weather is dry (HAHAHAHAHA) then i shall leave the cover partially open while i travel down to leeds to get my parents from the airport and see what happens!

Cheers guys

 

[gregdaisley]

I had this in my old car, it's so unsightly! I ended up removing the bumper, removing the light and brought it indoors overnight to let it dry out and temperature stabilise. Sorted it right out

 

[anarchy1515]

might have something to do with your hid wiring as that is breaking the seal around the edge of the cover

 

[Nath.]

I had this, I changed my sidelights and left one of the covers off by accident. Noticed it after some rain cos it was all wet inside. Took the cover off, drove the car with the xenons on for 20 mins in the sunshine, parked up and there was still a little left, went shopping and when I came back it was all dry. Popped the cover on and so far all is well.

 

[Jarre]

might have something to do with your hid wiring as that is breaking the seal around the edge of the cover

Possibly, but it went through the car wash the other day too. before i fitted my new sidelights, and it was fine. Today i got condensation and as i said earlier, the cover wasn't on properly, to i think that is what's caused it, also because its only happened on one side too and the HID wiring is the same on both near and off side! If it happens again, once i've got rid of it this time, i guess it is the HID wiring and i'll sort it out!

 

[Jarre]

I had this, I changed my sidelights and left one of the covers off by accident. Noticed it after some rain cos it was all wet inside. Took the cover off, drove the car with the xenons on for 20 mins in the sunshine, parked up and there was still a little left, went shopping and when I came back it was all dry. Popped the cover on and so far all is well.

Will try it tomorrow, thanks

I had this in my old car, it's so unsightly! I ended up removing the bumper, removing the light and brought it indoors overnight to let it dry out and temperature stabilise. Sorted it right out

I'll try what Nath said, I don't fancy taking my bumper off haha! But yeah, it looks a mess

 

[Jarre]

 

[sam7]

We have problems with the headlights on the cars and trucks at work having condesation in them due to the cleaners jet washing them. What I do is..

Remove the covers and put a towel or blanket over the headlight lens, turn on the lights and leave them on till the light is nice and warm then I blow through the light with the air line (but you could use the hair dryer on cold). Then I leave it and repeat if required. Usually takes a couple of goes but I have the headlight clear in the time a service takes (few hours). But you are left with water staining on the inside of the lens.

 

[Jarre]

I essentially did what sam7 said and it's all gone now cheers guys

 

[silverfox]

...apparently these little silica gel sachets you get in new shoeboxes and other packaging will sort out condensation problems in headlights. I've never tried it mind but worth a bash.

 

[rik_t]

...apparently these little silica gel sachets you get in new shoeboxes and other packaging will sort out condensation problems in headlights. I've never tried it mind but worth a bash.

Tried these with no luck.