About six months ago I had a leak in my A pillar drainage line (from the
sunroof) that was fixed, but now I'm getting an odor (swampy, musty smell)
out of the vents.  It comes and goes, strongest after a rain storm, and in
both economy and A/C modes.

The manual indicates that there's a vent area that should be disinfected:
Does anyone have any experience with doing this on their own?
professionally, and what the cost should be?
Anybody know if this could be related to a clogged drain line?