Q: What could be the problem?. The vent ducts are all clear.
A: i have Fixed a few of these where i have removed headlamp and drilled two 1/8 holes in base of headlamp to let water out and also to let it in effect breathe, also dried it out as best as possible at same time, normally takes about a week to settle down but i have had no further problems with my ones. To clear out the condensation quickly after drilling the holes drive with headlamps on and the back cover removed on a dry day so the water can evaporate and escape.