Fogging Problem Need Help

[BLITZEN]

When parked after driving in rain, my RS6 will fog inside so bad that it takes 15 minutes plus to defog and be driveable, or I need to towel off the insides of the windows. Is this a symptom of a leak?

The carpets all feel dry. It fogs while no one is in the car and the engine is off. It does not fog by sitting in the rain alone, (like in my driveway overnight), only after some driving.

Experience tells me that this will be a tough problem to solve since it has to rain to test if we've solved anything. So any personal experience you have will be greatly appreciated! What are all the things I should check?


Thanks!

[RS6-4dr911]

My theory, you're running without the recirculate on and are bringing in an ample supply of humidity. With the A/C cranked you're chilling the windows and when you shutoff the a/c from blowing the dehumidified air over the windows (keeping them defogged), the ambient moisture condenses. You might also try forcing the air through the dash vents only (or dash and footwell) instead of auto, which seems to divert quite a lot of air to the bottom of the front windshield.

Try running with the recirculate on and dash vents only and see if that fixes it. If it does, I guess I'm right, if not, I guess I'm blowin' smoke.

Good luck.

[intended_accel]

I'd also have the AC checked. If it's weak, you won't get the level of dehumidification that you otherwise would and apparently need. That, coupled with fresh air intake, would explain why it only happens after driving. Had the same problem with another car when the AC compressor failed to engage.

[BLITZEN]

In the past few instances, I haven't used the ventilation system for cool air, but instead warm air. Nevertheless, I will try to recirculate the air next time it rains and see if there's any difference.

The ventilation system seems to be working properly. I have no problems regulating the temperature cool or warm and no problems with the volume of air it's putting out.

Any other suggestions??

[Qisha]

Dear BLITZEN,

does your Car have a Solar Sunroof?

Qisha

[Rupert]

It sounds like this guy was having the same issue:

http://rs246.com/index.php?name=PNph...9402&highlight

http://rs246.com/index.php?name=PNph...578&highlight=

The conclusion:

They say they fitted two new temperature sensors (1 inside and 1 outside), a complete new wiring loom and many other parts relating to the HVAC system.

I have to say that on first impressions the problem is greatly improved, if not (it would seem) 100% cured.
The problem was that (as I said a long time ago) the interior fan was being powered by the sunroof even when it was raining/very damp outside.
This resulted in the car, that had just been switched off and therefore full of *dry* air, being pumped full of very wet air from the outside atmosphere, resulting in the condensation.

[BLITZEN]

Qisha & Rupert, YES, my car has a solar sunroof!

This diagnosis sounds suspicious. I will pay attention to fogging in sunlight vs. cloud cover. But wouldn't more owners complain about the same problem since so many RS6's came with solar?


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[Qisha]

Dear BLITZEN,

please let your local Dealer check the wiring for the Solar Sunroof. I would assume that two connectors have been interchanged.

If not - and you need further assistance - let me know.

Qisha

[BLITZEN]

Qisha, Thank you. I will pass that information on to my technician. Do you have any more details about the connnectors? Which ones are they and what do they do? And, may I ask, do you work for Audi?

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