Having a problem with front passenger floor getting soaked in heavy rain. Only seems to happen when rain is very heavy. Already had car at dealer twice. First time sent to body shop that sealed under cowl ?? . Did not work. Next time was told sunroof drain was clogged. Appears to be better but floor is still wet after downpours! Any ideas would be greatly appreciated since dealer tells me the next step is to remove windshield and dashboard at great cost (+ opening pandora's box)

 

If you can,
Pull back the floormat on the side with the leak then make yourself comfortable watching the firewall and side panel while an assistant sprays the outside with a hose and I mean floods it. If you have a flashlite and watch you may be able to see where the water is entering. If everything is dry when you start to do this place some talcum powder on the area and the leak will be easier to spot.

 

I have exactly the same problem on the 2006 Ford Taurus SEL (car has a moon roof). I complained to the dealer and he did a great job fixing it. The fix has lasted about a year. Time to add another bead of silicone caulking.

The problem is found in the plastic housing where the cabin filter is. The water (rain) drains down into the compartment and leaks inside the car just under the dash on the passenger side. When I complained about it, the mechanic new exactly where to look. He opened the cabin filter housing and ran a bead of silicone caulking along the bottom of it. The problem was resolved for a good year. It is now leaking again and I will have to do it myself this time. The extended warranty is now expired. I hope this helps.