I found several posts on this form related to a-pillar and windshield leaks, so I'm hoping someone can help me.

A couple of weeks ago, on a rainy morning, I found water on the passenger side a-pillar after going to a store for groceries. My car is always garaged, so I know this leaking happened while the car was in the parking lot. Upon returning home, I took some soapy water and tested all four drains in the sunroof for proper flow. All four are clean and drain quickly to the appropriate spots behind the wheels. There is no significant dirt in the sunroof track.

A week or so later, I was again out in the rain. This time I kept my eye on the a-pillar and in about four miles it started to become wet. The roof was properly closed, window fully up, door shut tightly, etc. Assuming that the roof drains are not the issue, where else can this leak be coming from? Note in the photo that the drop of water on door seal is not related to the leak, it was from getting in and out of the passenger side to take the picture.

 

More Information:

I ran two quarts of water through the roof drain in the right front where the leak is. There was no evidence of leaking. Then I drove the car a bit and the dampness appeared on the a- pillar garnish - it was not raining. I hadn't gotten any water on the windshield or roof. This made me suspect that the drain hose must be leaking, just a little. A couple of days later I pulled the trim off the door and opened the garnish enough to see in there. I didn't take the garnish off as I've not ordered the top clip that gets destroyed in removing it. I ran another gallon or so of water through the right front corner of the sun roof, again being careful not to get any water on the roof or windshield. No water came into the a-pillar and the garnish did not get wet. I could not observe any water in the area of the drain hose, which runs inside the airbag in the a-pillar. I'm stumped.