# Xenon Light Problems



## Hanshi (Oct 27, 2006)

I have a 1998 A6 with Xenon Lights. The headlight unit is "fogged up" and it really impacts the brightness of my lights. I have tried to clean off the outside of the headlight housing, but the problem must be on the inside as I have not been able to clean it up. Have been told by Audo Service that I would need to replace the headlight housings.
Anyone else have this experience, and any suggestions?
It looks like if I can not clean up the housings, then I will need to get replacement units. As the car is wired up for the Xenon lights I was looking at new replacement housings (w/o bulbs) and use my existing bulbs. Another option would be to purchase new Halogen housings and bulbs. The housings appear to be identical, but has anyone done the wiring to shift back from Xenon to halogen lights?


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## GLS-S4 (Jun 6, 2005)

*Re: Xenon Light Problems (Hanshi)*

I would recommend keeping the Xenon's, you may be disappointed with the Halogens.
Do you know what is causing fogging inside lenses, moisture or dust or ?
If not sure and just throwing this out there... you could try pulling a lamp out and using a Q-Tip to sample the inside of lense...


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## Hanshi (Oct 27, 2006)

It appears to be moisture, but the light housings are always fogged over and worse when they get wet in the rain.


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## GLS-S4 (Jun 6, 2005)

*Re: (Hanshi)*

Perhaps check all lamp fittings to ensure they are seated. Bulb work maybe done in high humidity conditions. The headlamp assemblies are basically waterproof.
I've seen high humidity get trapped in headlamps, then condense on inside of lens when cool. Could try opening a lamp fitting and use a fan to get dry air flowing.


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## CE (Jan 21, 2001)

*Re: (GLS-S4)*

Replace the entire assy. they have vents to eliminate moisture. I just replaced both assys on my 2000 A6, the lens where all yellowed sand blasted from highway, BIG improvement in light on the road, not that hard to do, just have a service manual. the improvement is dramatic. The heat from the lamp over time discolors Polycarbonate lens. Outgassing of the plastics inside cause the grey film to accumulate inside the lens and reflectors, also dropping lite output.


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## Hanshi (Oct 27, 2006)

CE:
Thanks for the input on your experience with the lights. I have decided to replace the assemblies. Should make a big difference.


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## GLS-S4 (Jun 6, 2005)

*Re: (CE)*


_Quote, originally posted by *CE* »_they have vents to eliminate moisture.

How does the vent eliminate moisture?
I thought it would balance internal / external air pressure for diff altitudes.


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## CE (Jan 21, 2001)

*Re: (GLS-S4)*

The entrie assys where not all that expensive either, from the dealer(VW for me). With the service CD manual, it shows all the hidden nuts, screws, clips and what needs to come off to get to the bottom bolt holding the lamp assys. I also changed em out on my 96Passat, they where really yellowed with age, I made em worse by using a plastic cleaner claiming to restore them, it ruined em. The Passat was much easier, couple screws grille, trim strip snapped out, Audi has a few more hidden scresws and stuff on the bumper cover, to allow access for the assy to pull out only 3 bolts onlight itself my A6, but it couldn't swing out unless the bumper cover was moved forward, it really is easy, just take your time and do it right first time, and nothing gets damaged. Big improvment in visibilty with new CLEAR lens. well worth the effort, but get the service CD or book, it makes it easy. Otherwise you will never know where some screw or bolt is that is needed to be removed, and you wind up messing something up.


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## GLS-S4 (Jun 6, 2005)

*Re: (CE)*

Understood. I've R&R'd a few sets of B5 A4, B5 S4 and C5 A6 Headlights, pretty straight forward with three screws each. I've never had to pull a bumper cover. Dropped the lower screw once but spring loaded retrieval tool took care of it in minutes, handy for headlight work.
I'm still trying to figure out how a vent removes moisture...


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## CE (Jan 21, 2001)

*Re: (GLS-S4)*

The lower edge of the halogen type lamps assy will not tilt enough to pull it out. The bottom screw bracket is about 1" below top edge of bumper cover, so the assy will not pull out, nor will a new one go in. this is on a 2000 A6, don't know if other models are similar, maybe not. Not until i pulled up the CD manual did it specifically tell you to pull bumper cover to remove headlite assys. I was trying to pull it out before looking in CD, and it would not come out, even though all 3 bolts are easily accesible from top. Once the cover was pulled forward about 10 or so inches, assy pulls right out. The manual was right. Without a vent, where does the moisture go, once it's in there.? Plus the outgassing from the plastics over time with the very hot temps from the lamps would cause pressure build up wouldn't it, gotta vent it?condensation no headlight assy is perfectly air tight, it's sealed but over time it does not remain air tight, so they vent it, moisture comes and goes. What would pressure in altitudes have any thing in a headlight? Tailights are not sealed, the lamp holders do not seal with a gasket, so they are already vented. Headlamps have gasket around the bulb and the rear cover is gasketed, the insides is surely sealed, but not air tight, the moisture from condensation, between hot lamps, cold housings damp weather, moisture has to go somewhere. Check with Hella, ask them what the vent tubes do.


_Modified by CE at 2:16 PM 10/29/2006_


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## GLS-S4 (Jun 6, 2005)

*Re: (CE)*


_Quote, originally posted by *CE* »_Without a vent, where does the moisture go, once it's in there.? Plus the outgassing from the plastics over time with the very hot temps from the lamps would cause pressure build up wouldn't it, gotta vent it?condensation no headlight assy is perfectly air tight, it's sealed but over time it does not remain air tight, so they vent it, moisture comes and goes. What would pressure in altitudes have any thing in a headlight? 
_Modified by CE at 2:16 PM 10/29/2006_

Interesting philosophy regarding automatic moisture venting... I guess mine don't work because when I got humidity inside sealed headlamp assembly, it did not remove itself automatically as you described it should. I had to pull a bulb and use a small fan to stabilize ambient humidity with internal headlamp humidity - this removed the moisture that was continually forming on inside of lense after a bulb change outdoors in cool weather.
Altitude pressure differences are significant between sea level and say 5000' ... check with an aircraft pilot or meteoroligist for pressure differences at different altitudes, or just ride a fast elevator in a tall building.
Do you have any pictures of the moisture removing vents you describe ?


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## CE (Jan 21, 2001)

*Re: (GLS-S4)*

No pictures, I threw out the old assys. It's a right angle black rubber tube on the headlite assys. The assys on my Jetta are not vented, it's a 98. Check with Hella, they make the assys. I've seen the same black right angle tubes on other cars too Pontiacs and Chevys .


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