Water pooling in passenger side floorboard
A few days ago I'm dropping DW off at work when she mentions that the bottom of her backpack (which was sitting on the passenger floorboard in our car) is wet. That's weird, and reminds me that last week, I noticed my socks were wet when I got out of the car, though I didn't think too much about it at the time...
With a sinking feeling I drive home, park, and walk around to the passenger side. As I suspected, the passenger floormat is completely soaked. Bad sign. Okay, take it out, check the carpet... also sopping wet. So I pull up the carpet to find my worst fear confirmed - there must be half an inch of water sitting under there. And I don't know how long it's been in there, because the wet-sock incident was more than a week ago.
This is really an extremely unpleasant discovery.
Visions are dancing in front of my eyes of the whole car infested with mold, having to rip out and replace the entire carpet, terrible things... I don't want the fine people of this forum to think I'm dramatic but I'm already on my knees at this point to look at the floorboards and there may also be some shaking of fists at the sky and cursing the gods, et cetera...
Anyway, I go grab a few towels to soak up the water, prop up the carpet as best as I can to dry it out, and try to figure out my next step.
The internet tells me that corollas commonly have an issue with their AC condenser drain hose getting clogged up, and because that hose runs under the passenger-side dash, it can end up leaking into the floorboards. We've been using the AC off and on so it would at least make some sense. Fine, the hose is easy to find but when I disconnect it it's dry and when I try blowing into it there doesn't seem to be any resistance. I'm doubtful that this is the issue.
So I call my dad (who, conveniently, is an auto mechanic), and he asks me if it's been raining recently. It has been, so he tells me to check the drains for the windshield and the sunroof. Ideally, the way to do that is to have someone spray a hose onto various part of the car while I'm inside looking for leaks. But we live in an apartment downtown so we don't have access to a hose and the nearest DIY carwash that has one is out in the suburbs somewhere through the hellscape that is DC traffic.
So this is how I find myself, ass literally up in the air, contorting around to shove my head under the passenger dash while my DW pours various potfuls of water that we've shlepped out onto the car while I attempt to find where water is getting in. I'm also being swarmed by mosquitos because late-summer DC is a literal swamp, not just a metaphorical one.
At this point, I'm mostly just thinking that however much money I'm saving by doing this myself isn't worth it.
Thankfully, pouring water on the car at least replicates the issue so we can confirm it has something to do with a seal or a drain. It's hard to for me to tell where water is getting in - there's nothing obvious. The only thing I can see is a tiny little drip coming from a piece of tubing that runs out the bottom of the passenger-side A pillar. Thankfully, that's enough for my dad to conclude that it's probably a sunroof drain issue. I confirm his suspicions by pouring water directly into the right side of the sunroof seal, which causes a flood of water to come out of the aforementioned tubing. Finally, we've at least isolated the location of the problem.
Diagnosis: a clogged sunroof drain, which runs down the A pillar into the wheel well, is causing water to back up and get somewhere it shouldn't be.
Fix: clean the drain.
Now for the final hurdle: I can't find the sunroof drain. Despite sticking my head through the sunroof, which puts my eyeball about an inch away from the supposed drain location, I can't see it. There's some silt in there, but no big debris that could be blocking anything. My dad insists that there should be a drainage hole in the front corner of the sunroof, so in desperation I start poking around with a screwdriver. Sure enough, the silt I mentioned, which is the exact same color as the sunroof plastic, is covering a tiny drain hole in what I would have sworn was a smooth plastic surface. Frustrating
The silt is easy to clear out, and then I feed some trimmer line into the drain just to make sure there aren't any blockages further down. I don't find any resistance and the line comes out clean, so I feel confident the silt was the problem.
I confirm that the issue is fixed by pouring some more water in the sunroof and making sure it finds its way to the wheel well rather than the car interior.
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Closing thoughts
Compared to some of the other fixes I've posted in this thread, I didn't enjoy this one at all. I was trying to think about why that was. These are the factors I came up with:
1. Time pressure
It rained every day this week, which meant that every day I didn't get this issue figured out was another day of water getting into the car. I was walking around all day with the sword of mold-o-cles hanging over my head, which is not a fun way to live. This factor was compounded by factor number 2...
2. Challenging / ambiguous diagnostic process
At each step of this process, I was blocked by my inability to effectively root-cause the problem. Even when we poured water on the car to replicate our issue (the correct approach!), the water entry point was covered so I couldn't see it and it barely dripped because we had the sunroof closed. I would never have been able to make the jump to the sunroof drain being clogged without my dad's expertise.
So most of the time spent on this fix was just me banging my head on the wall trying to figure out what the problem even was.
I was reminded of the parts of software development that I hated the most - the parts where something isn't working, but everything you know says it should working, and WHY ISN'T THIS WORKING???? HOW CAN IT POSSIBLY NOT BE WORKING, IT HAS TO WORK, AHHHH@#!$@#!$. This process gave me that same feeling.
The combination of 1) being under the gun to get something fixed ASAP while simultaneously 2) not being able to diagnose the issue... not enjoyable.
3. Lack of payoff
When I fixed my coffee grinder, my reward was a tasty, freshly brewed cup of coffee. When I cleaned the rust off of DW's bike fenders, there was a real satisfaction in seeing the rusty metal come back to life. I literally held them up the air and went, "Ooo, shiny!" In this scenario, my reward is that my car is exactly the same as before, except now maybe it will have mold issues going forward. Great...
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TL;DR: clean your sunroof drains and pay someone else to be your auto mechanic.
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Photo evidence
The scene of the crime. I should have taken a picture before cleaning up the water so you could see how much there was but I didn't think about it.
The A/C hose (not the culprit):
The actual entry point:
Cleaning the sunroof drain with trimmer line:
