Long-time browser of the forums for help, been able to fix a lot of problems on my 240 that way, but this one's got me stumped.
In the passenger side of the trunk, I noticed a dripping noise; after some inspection, it looks like it's coming from a black hose behind the wall panel. This hose runs right next to the rear vent, but appears to continue forward into god-knows-where, and I figured I'd ask here before tearing everything out.
This hose is dripping cold water into the well, which is draining out through another separate hose that I've gathered is normally connected via a third clear hose to the sunroof. I have no sunroof, and so no clear hose, but I do have the short black hose draining out the well, nonetheless.
Here's the main thing that's got me stumped: it hasn't rained here in weeks, so the water has to be coming from the A/C system, or the rear windshield wiper, or... what, exactly? What is this hose, what is it draining, and should I be concerned?
Let me know if pictures or other info would make this clearer.

 

Does your squirter for the rear window work?

 

Sorry for the late reply, diagnosed the issue but still working on the fix. Not only does the rear squirter no longer work, the front one doesn't either. Just got a jug of washer fluid today, going to see if the pump just went kaput and let everything drain out, or there's a hole in the line, or what. Will report back with findings.

UPDATE: Yup, it's definitely the hose for the rear squirter. Looks like there's a leak in the piece where the fluid gets diverted upwards. Probably not something I'll tear everything out to fix (rarely have needed that working), but something to put on the to-do list.
Attached is an image of the culprit, mid-leak.

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UPDATE 2: I am not a smart man. Apparently this is the check valve for the washer, and should be an easy replacement.