I noticed a wet spot in my passenger floorboard after a hard rain. I'd just had my windshield replaced, so I assumed it was the cause. When I spoke to the windshield guy, he said it's probably a clogged drain that's backing up and leaking in under the dash.

According to him, rainwater is supposed to hit the windshield and flow into this drain and out at the bottom of the truck. If this is true, any idea where this is located, and how the clog can be removed? Is this a diy deal, or should I see a mechanic?

HELP!!

 

The drain is under where the heater hoses and ac lines come out of the firewall. May be clogged with leave sand debris. The wiper cowl drain comes out down below the fender.

 

Thanks. I'll see if I can take of that myself.

 

I just fixed mine today. After a good rain floor mat was wet, look under dash could see water dripping off HVAC case. After using the water hose and spending 3 hours I found that there is a black clip at the bottom of the windshield on the passenger side. I believe it there to align the windshield when installing a new one. Anyway it looked ok. But when I pulled it out you could see the rubber gasket under it had failed. Also the bottom of the clip has a slight groove in it that helps channel the water inside. I popped it out cleaned it up put some silicone on it and reinstalled it
On the driver side there is also a clip but it has no gasket because the hole does not go in to the interior.

So you only have to check the passenger side one. I would just pull it out and reseal the passenger side one. You really cant tell its not sealing by looking at it.

I'll attach some photos
Hope this helps