I had to replace the airmatic suspensions on both front RT/Lt, IThe blower motor was replaced in 2005, now it is out again. I have had to have the computer repalced, there is a link under the front passager's dash and the repairman don't know where it is coming from.
There is a water lesk under the passager's front dash! on 2001 Mercedes-Benz S430
by lady-myrna in Norcross, GA on August 22, 2013
ANSWER by Tasman123 on April 10, 2014
I had the same problem with my 2001 S430. There is a faulty drain under the dash. When leaves accumulate out front out the windshield. There is a class action lawsuit for this issue. Contact Mercedes Benz.