Audi S8 Rules

Hi guys... so my 2002 S8, with 217,000 miles on it seems to be having a few issues. I replaced the fan motor a few months ago.

My issues are usually in very cold weather around -20 deg. C or 0 deg. F. Usually it seems the control module doesnt compensate fan enough to keep it from fogging up. Sometimes your feet get cold. etc. this is the AUTO mode. if I put in manual it works fine. I noticed a few years ago, if I drove from outside cold temp into a heated carpark, the vehicle would not fog up, which I assume is due to the Auto Recirc function when turned on!? but now it will fog up all the time. If I'm driving down the road sometimes it will start to fog up if I have auto recirc on, if I turn it off usually it would clear. Sometimes when I start the car, the display of the set temperature the pixels are all jiberish and screwed up.

Is this the main head control unit in the car!? or other module issues?

Also when I replaced the fan motor, I noticed an aluminum sensor I assume that has vertical aluminum round pins sticking up. Is this a moisture sensor for the Auto recirc?

Thanks guys!

spitanddirt

The aluminum "sensor" you are talking about is not a sensor at all, it's most likely the blower fan resistor. The pins are heat sinks to draw heat away from the resistors that allow different fan speeds.

If you are getting fogging when Defog is selected, it's possible that your A/C isn't charged enough. I usually have to add about one 12 oz can of Freon about every other year in the summer time.

During Defog, the A/C is turned on to remove humidity from the cold outside air that has been warmed up first. Of course, you have two heater cores and one electric coolant circulation pump for each heater core located on the driver side of the fresh air intake under the hood. If a pump motor fails, you will get only one heater core providing heat. The only way to test without taking things apart is to run an Output Test using a Ross-Tech scan tool.

Every once in a while, my display will go nuts until I restart the car. It's probably dust building up on the control circuit board. Btw, I have a 2000 A8

silverd2

If the evap housing drains have never been cleaned out >>

audipages Unclogging the A8 Evaporator Drains

Audi S8 Rules

Thanks for the info! I'll try that.

Audi S8 Rules

Thanks for your reply...this might be part of my issue as I had the A/C recharged last year, the A/C pump is weak and normally wont work properly for the first couple of weeks of spring here...seems the seals dry out and it takes a little to get them lubed up and seal again!? I have a replacement pump that I might have to throw on it.

Audi S8 Rules

Hi guys. My "02 S8 heater controls seem to be going. If I put both sides on Auto mode, I will get spratic heat issus, sometimes cold feet, sometimes it will just start fogging up, it has a mind of its own. The heat output doesn't seem as good either and I don't think the fan blows as good as it use to. I have replaced the fan motor so its works ok. I recharged the A/C this summer. If I select the heat directed on low or your feet and then select the high one as well taking it off auto mode, its at least stable. I used to be able to drive around summer or winter with temp set at 19.5 deg C. Now I have it on 21 deg. C for winter. The auto circ doesn't work well either. Is all this coming from the main in dash control unit? or is there a separate computer or module that is going?
Cheers!