Can't figure out why water on pass. floor on my 98?
 

So I've had this water leak for years now. I've never figured exactly where it is coming from. It's getting annoying. I've read about the common places on Rangers with the third brake light. Which I believe is leaking on mine because the bottom edge of the headliner around it is all getting dirty. However, the worst part is the passenger side middle of the floor. It's most definitely not a heater core or a clogged A/C evaporator tube. Those have been checked numerous times. I also watched some videos about the pocket under the front mudflap getting caked up with debris. I took mine off and it is totally clean, not even dirty. I took out the passenger seat and lifted up the carpet to see if a plug was missing but they are all there. I believe I've narrowed it down to it's trail. It's coming down somewhere above the passenger kick panel. It starts at the carpet there and then flows into the middle of the floor. There is no water residue under the seat, sides of the transmission tunnel, or bottom edge of the door sill. It was all dry up until my hand got to about the middle of kick panel and then followed into the middle of the passenger floor. Where are places I need to check? How do you fix the roof brake light leak? Do you just get a new assembly? I don't see what fails on it. There's not much of a seal.

There is a area on the bottom passenger side of the windshield, above the computer, that's known to leak.
Also check the radio antenna to make sure it's base is properly fastened down.
Let us know what you find.

How do I access the area on the bottom passenger side of the windshield? Or do you have to get a windshield guy to do it? I'm pretty sure I can check the antenna. I do notice the top back of my headliner is getting dirty from where probably the roof light is leaking but I haven't replaced it. What leaks on the roof light? I see they are common. I can't figure out the passenger side floor leak. I tried soaking the outside of the truck in that area with the hose for minutes and I saw no water trail. I can't even find the source of the water trail leading to the center of the passenger side floor. It's just like it gets wet right in the middle of the floor. I don't even have any trees in my driveway for the cowl to get clogged. I didn't see any missing floor plugs on that side. It is annoying because I want to replace the carpet because it's original and now smells but I must stop the water leak first.

Open the glove box door & remove the fasteners that hold the glove box in place, then remove it & you can see the bottom of the computer. Remove it & you can observe the lower right/passenger side area of the windshield. When it leaks there, the computer often gets wet too.
Good idea to try the water hose.
If all else fails, you could close all windows & set off a smoke source inside, then look for smoke leak signs outside.

How good does that smoke test work? I could try that. I know it can't be the evaporator box because I checked it one time. What's the best way to get access to make sure the evap box isn't clogged with leaves? I know I've had to haul yard debris off over the years and usually have the driver's window and the sliding rear window open which sucks all kinds of debris up over the dash. I forgot about that.

I have this problem on both of mine. Its maddening. I honestly cant see how you would get smoke to come out of what is essentially a "complicated weep" of a hole without a lot of specifically applied pressure

If you are going to replace the carpeting anyway, remove it. Tape some butcher paper down and you will find the source of the leak faster. Start a few tests, hose test, a/c test, heater test. Remove the glove box as pawpaw said and put some paper in there. Does the water smell like antifreeze, then it is heater relate. It doesnt? Maybe evap related. If it leaks when it rains, windshield or etc. If it leaks when it doesnt rain, start over

On the evaporator box question, if the carpet is wet year round/even when the AC isn't used, then a clogged condensate drain belongs low down on your suspect list.

In case you have more than one problem, On a warm humid day, when the AC is being used, look outside underneath the center firewall area where the AC rubber condensate drain protrudes through the firewall & see if condensate is dripping out, or its damp there.

On the smoke test, turn the air duct to outside air, fan speed on High speed & close the doors & windows to pressurize the cabin & look for smoke signs around window & door seals.

More thoughts for consideration, let us know what you find.

I took a look at mine and when I take the glove box down I can barely even see the computer and dont see how removing it would give a much better view. Am I missing something.

Review post #2, as reported leaks in the area are known to wet down the top of the computer, so removing it & having a helper flood the outside passenger side of the windshield with a water hose might tattle on a weep there that's easier to see if the computer is removed.

Do you think it would be easier to see from the engine compartment? I bet with the computer removed you could get your hand in there pretty easy.

just as another line of thought, where is the drain tube for the cowl on these trucks (assuming one per side)

On my 02, I have a small leak at the top of the windshield on the passenger side. During heavy rain, you can see droplets of water running down the inside of the glass to the back side of the dash. I wind up with wet carpet on the passenger floorboard. I haven't chased it any further than that since I plan on getting the windshield replaced soon since it has a crack in it. If I get wet carpet after that, I'll look more into it. Just keep in mind, there are plenty of places water can work it's way down from. Maybe pull some trim pieces, stuff paper towels into the exposed holes in the body, hose the outside down and see which ones get wet. Find a wet one, go up from there until you find dry. A little labor intensive, but may help narrow the search area.

I don't see any signs
 

I took out the glovebox and didn't see anything wet or damp. The foam sealing the a/c box was dry and there was no debris behind the blower motor. I lifted up the floor mat saw it was damp in the middle but I can't see where the water begins. It was raining today. When my passenger side floor does get wet it doesn't get soaked just damp. What about removing the carpet would it help? It doesn't matter whether a/c is on or not.

We checked under the carpet again and seems to originate under the center of the a/c box near the trans tunnel. My friend said the drain pipe might be backed up. I stuck a flathead in there and nothing came out. So how do I find out if the box is full of water and what's causing it not to drain.