Lighting - Moisture Accumulation In Headlamps
94 Moisture accumulation in headlights
94 13 11
2028277/6
March 6, 2013
Supersedes Technical DIAGNOSIS AND REPAIR Group 94 number 13-01 dated January 2, 2013 for reasons listed.
Vehicle Information
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Condition
^ There is considerable moisture present in the headlamp (Figure 1).
^ The moisture disappears only after extended drives (greater than 10 minutes).
^ There is no external damage to the headlamp which could introduce moisture.
Technical Background
Humid air settles on the inside of the glass, causing moisture to appear on the inside of the headlamp lens.
Because of the headlamp circulation system, outside air is allowed to flow through the headlamps. The open, water-protected ventilation system
(needed for pressure compensation) creates different "climate zones" inside the headlamp, where the lens is either warmed up by the light or cooled
down by passing air.
When high air humidity and temperature differences exist between the inside of the headlamps and the outside, condensation can form on the inside
of the lens, especially in cold and wet weather. This moisture buildup can happen, for example, after a car wash, after steam cleaning of the engine or
the front end, or after overnight temperature changes.
This condition is more easily visible with headlamps made from clear glass. The moisture is an optical condition which does not affect the headlamp
function (light performance) and does not lead to corrosion or damage of the internal headlamp parts.
This condition is common to all exterior vehicle lights, and can occur on every headlamp, fog lamp, or rear lamp.
Production Solution
^ Optimized headlamp ventilation hose placed into production for all xenon headlamps.
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^ Charge air ducts placed behind intercoolers.
Service
1. Remove the headlamps and dry the inside using compressed air or a hot air blower. Check for any loose caps, loose or unsealed control modules,
or cracks in the headlamp housing(s) as the culprit of moisture exposure.
2. If the vehicle's build is prior to VIN # *CD004736 and the updated ventilation hoses are not currently installed, replace the headlamp ventilation
hose for each headlamp with the new part number to help reduce any further humidity ingress into the headlamps (see Required Parts and Tools,
below). Otherwise, proceed to step 3.
Tip:
The updated ventilation hose can be recognized by the integrated filter (Figure 2, arrow).
Tip:
The updated ventilation hose is not connected directly to the headlamp housing. The house routes downward from the headlamp carrier and between
the radiator and bumper (Figure 3, arrow).
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3. Cut two sections of butyl cord sealant, each 8cm long (Figure 4).
4. Each headlight ventilation guide tube must be sealed to protect against further moisture ingress (Figure 5).
5. Wrap butyl cord sealant around the left and right ventilation tubes, taking care no block the air passage tube (Figure 6).
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6. Knead the butyl cord sealant in place. The butyl sealant must be excessive enough so that the headlamp housing squeezes it and creates a robust
seal at the housing (Figure 7).
7. Leave an uncovered section of the air tube so that there is no chance the sealant will clog the air passage tube (Figure 8).
8. Reinstall headlamps. The headlamp housings will take more force than usual to install, as the butyl must be compressed down and backwards.
Tip:
When installing the headlamp, do not work back and forth during reinstallation, as this will disrupt the butyl seal. If the seal does get disrupted,
remove the headlamp completely and knead the sealant back in place to ensure a good seal.
Tip:
If the headlamps were removed after the butyl cord was already installed from a prior procedure, remove the old sealant and replace with new
sealant.
9. Check vehicle for left and right air ducting for exiting air behind charge coolers. Vehicles built from June 2010 will not have these exit air ducts
installed. Check vehicle regardless of build date. If air ducts are not installed, continue with steps 10 - 14. Otherwise, proceed to step 15.
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10. Remove front wheels and wheel housing liners. The rear of the charge air coolers will be exposed (Figure 9).
11. Locate exit air duct attachment hooks on the left and right air charge coolers (Figures 10 and 11).
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12. Affix left and right exit air ducts overthe rear of the charge air coolers (Figure 12).
13. Inspect exit air duct attachment points to be sure that ducts are engaged properly over charge air cooler hooks (Figure 13).
14. Reinstall wheel well liners and wheels.
15. Please inform the customer the new ventilation hoses and sealant are only to help reduce the moisture condition, but will not eliminate the
condition completely. Moisture in the headlamp lens is normal and can occur even with the improved filtration.
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Warranty
All warranty claims submitted for payment must be in accordance with the Audi Warranty Policies and Procedures Manual. Claims are subject to
review or audit by Audi Warranty.
Required Parts and Tools
Additional Information
The following Technical DIAGNOSIS AND REPAIR (s) will be necessary to complete this procedure:
^ TSB 2012749, 94 Exterior lights, moisture accumulation
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service
manuals for the latest information.
