Is it definitely coming down the a-pillar? As in, you can see it doing it? Or is it appearing lower down and you think it’s coming from the a-pillar?
Edit: you posted before I answered. Soz.
No all good. I always ask that question of myself - "where is it really coming from?" In this case I still have no idea.
I thought it was lower down initially and removed the drivers vent cover. OK, now coming out of the bottom of the A-pillar cover.
Removed the A-pillar cover. Now coming out where the A-pillar cover meets the start of the headlining.
I'm thinking, "how the hell does it get there"? I was pretty confident it wasn't some weird leak in the roof of the car (rusted out channel), but checked anyway... Gutter strip off (needed a clean anyway). Nah, all solid.
Therefore, you're quite right to question me exactly where its coming from. Because, in reality, I don't know! I really don't want to rip into the headlining!