I have 1 1999 old body style GMC. It leaks water on the passenger side floor when it rains or I wash it. It looks like it drips from the blower motor. Any thoughts?

have the same problem with my tahoe, have yet to find it.

If your truck has power door locks and windows check the rubber boot that allows the wires to pass from the door jamb to the door. They can become dislodged allowing water to seep through.

I had the same problem with my '99 Tahoe, dripping from the blower motor housing. Drove me nuts. I could spray all day with a pressure washer or water hose around the doors, windows, windshield and never a drop would fall inside. But after a hard rain, or drive on wet roads I would almost always have a puddle in the passenger floorboard. I took all the carpet up, plastic panneling, seatbelts rubber door gaskets and still couldn't find where the water was coming from. While I was staying at a RV park an older gentelman came over and asked what the heck I was doing spraying water unter the Tahoe. He said, no problem I'll fix it. He opened the door, picked up a 4x4 and placed it at the bottom of the door and pushed very heavily on the top of the door. He then opened the door and took the 4x4 out and told me it was fixed. I had that WTF look on my face until he told me he just retired from GM as a QA\QC man and sometimes the door just need to be "adjusted". It has never leaked again.

Mine I get water in the blower motor just by pooring water right on the cowl black plastic grates. So the other day After I made the post I went back to work after lunch and had some time to kill so I pulled the cowl plastic grate under the wiper arms up. Looked down inside and saw the fresh air duct sticking up through about 3 inches. I knew there was no way water was getting high enough to go over that. So where 2 of the screws hold the cowl plastic grate I fed a coat hanger down through the hole to see if it went right into the blower case. Sure as sh*t, I had the blower motor on low and fed the coat hanger down through the screw holes and all of a sudden grrrrrrrrrttt. The coat hanger hit the blower motor. And then when I looked one of the holes I was missing a screw. I never took one out of there. So I got another screw and put RTV on both of the screws that are over the inlet and put the cowl plastic cover back on and last night and today have been the strongest rains this season and today I drove around quite a bit and no drips at all. So hopefully I'm fixed. Hopefully between this and the and neverenuf post it will stop the drips. My buddys 99 leaks as well so hopefully one of these fixes will fix his as well.

Good deal. Hope that does it for you.