So the Symphony head unit in my 01 A4 Avant QTM stopped receiving radio stations recently. Figured I'd have a look at the antenna booster in the cargo area. Oddly, everything in that nook was... moist. There was condensation all over the antenna booster, CD changer, subwoofer enclosure, etc.

Let the good times begin!

I removed all the trim around that area and pulled the subwoofer enclosure. Hmmm... funny rattling noise inside, wonder what that's all about.

Took the subwoofer out of its enclosure, and the entire box is filled to capacity with empty nut shells. Apparently a squirrel once made its nest in that part of the cargo area (must've been years ago before I bought the car) and was throwing all its empty nut shells into the subwoofer enclosure through the vent tube in the side. Mr Squirrel also took the opportunity to chew on the wires in there. Not enough to break them, but enough to get them bare in places. Must've been a small squirrel to get through that tiny vent hole...

Back to the "moisture" that started all this... there was a big puddle of water under the CD changer. No clue where the water is coming in from. It doesn't appear to be from the tail light, or any of the rear windows. All those areas seem to be nice and dry. There was also a bit of water under the spare tire, but that may have just been condensation that made its way there from under the CD changer.

Floating in all that water... dozens and dozens of empty nut shells. Also, a wet and nasty bundle of shredded crap (insulation, tissue, paper towel) that once was a squirrel's happy home.

I guess I should count myself lucky that there wasn't an actual squirrel in there... or a dead one.

But where could all that water be coming from? None of the body plugs on that side are missing, none of the window or door seals appear to be compromised, the sunroof drain tube is on the other side. The leak doesn't seem to be coming from very high, the insulation pads along the body panels were only wet along the bottom. Could it be that plastic vent thing along the bottom edge? I know none of the stuff in there was wet 2 weeks ago, and the car just sat there for those 2 weeks, not being driven at all. But it did rain a LOT during those 2 weeks.