A/C condensation not draining properly and water spraying onto feet

I have a 2002 Audi S4 with the same problem (passenger side only) I noticed that after heavy rains I hear sloshing water behind the dash and water dribbling onto the floor mat on the left side or the passenger floor mat. Dealer was stumped, independent audi repair man stumped. So here's the deal - recently I replaced my battery only to discover that in the battery compartment underneath the battery and battery holder there are two large drain holes, one directly under the battery and another a foot or so toward the driver's side. These holes were both plugged, basically from leaves and debris that had worked their way down in there over time. There is room for a lot of water (several quarts at least) in the battery well if these drains are plugged. When it gets full it drips into the passenger compartment, in my case always on the passengers side. I have had to clean these drains every six months to a year since my car had 20,000 miles. (now has 75,000 8 years old). Check it out - you can only access by removing the battery and battery holder.

You can actually perform the 'Audi TSB' for fixing this problem with a jack and a long prybar. You raise the passenger side up and knock the drain plug/filter out from its hole. And yes this is a known problem and that is the fix directly from Audi.