MkIV Jetta - Removing humid/water dmg smell

I think either the door seals or the rear window seal is going bad and/or is rotten because I have a constant rotten smell in my car that smells like moldy/mildewy water damage. It goes away after a while of airing out the car, but as soon as it sits for a few hours with doors shut/windows up the smell returns.

I'm up for anything short of selling the car that will help fix this. All new seats/cards/seals/etc.

I can't find anything on this in the forum (I have honestly tried) so anyone with prior experience or guesses would be helpful.

Thanks all.

Gotta find the source. Just don't treat the smell.
Think sunroof ac vents, cabin filter.

Pollen filter ? In my mk5 the pollen filter was realllllly old and made the car smell terrible . It has been a few months since installing the new one and the smell is gone.

Spare tire well can hold water if you have a leak.
Cheers

Thanks for the suggestions. I'll be investigating today and if I find something I'll post for further diagnosis.

Not sure what to check with the ac vents though.

AC vents, turn on the blower. Does it make the smell worse?

If your car had any water leaks in the past the sound proofing under the carpets are probably soaked.......no amount of airing it out will help.

Pull up the carpet where you can and try to feel under the sound proofing mat for wetness.

You will have to remove 1 of the front two seat ( pending on which side is wet ) and pull the carpet back, on my car is strategicly cut the carpet so I didn't have to pull all kinds of interior pieces ( you will see if this is the route you take ) and cut out the sound proofing too.
I've left my soundproofing out of the car in the sun for two weeks to let them completely dry and left the carpet folded back with a dehumidifier running in the car over night, then found the leak and fixed it.

Usually either side is wet, and it's front , back or even both front and back, but usually on one side , at least with my stable of cars.

If your car has a sunroof then you should check the sunroof drains. There's one at each front door, near the hinges. You can see it with the door open. There are also some under the rear bumper somewhere.

In my car the front ones got clogged and water drained down the A-pillar and into the carpet. After I unclogged the drain hose, I used a carpet cleaning machine to suck up as much water from the carpet as I could, and then I drove for six hours with both the heat and A/C on full. (Had to do a trip anyway, and it was winter so the heat was okay.)

It has been fine since I did that. Smelled like rotting cabbage before.

Mike_04GolfTDI / csstevej called it I bet. Back in the dealership days, we use to have a lot of smell issues related to leaks or evap drain being clogged. There are a few sprays you can use for the AC. Mold is tough as it will get down in the padding. You can try and use a shampoo approach. I would also recommend looking at using an Ozone machine to kill off the smell and any mold spores that are accessible. Ozone works fantastic, BUT you cannot do it a bunch due to what ozone will do to degrade plastics and rubber. ( a bunch meaning regular use )

hey. so checked all the carpets, nothing is wet. the upper deck behind the back seats is kinda wet... not soggy but it felt a little wet. i don't have a sunroof so no problem there. the only other thing i can think of is maybe the seats have gotten wet. when the ac is on in the car or just the fans only, the smell gets better. i didn't get to check under all the carpet so maybe a small bit of water is standing under somewhere. Busy weekend didn't leave me enough time for a full inspection. So hopefully more to come tomorrow if it doesn't rain too hard. Also, we haven't had rain in a while, so maybe if there is a leak, a heavy rain the next couple days might help me find the culprit easier.

I found the mat under the carpet can be quite wet even though the carpet feels like it is dry. You have to pull up the carpet to expose the mat and dry it really well. A fan helps, as does a string of hot days, fan blowing, and windows open.

Of course, it is all for naught if you can't find the leak.

One place you can try is the interface between the cabin air filter base and the body. The mount is a plastic piece that fits into an opening in the body, and if there's a leak at that point, it will allow water to leak into the passenger side footwell whenever it rains.

Other possibilities are all the door seals.

Good luck; tracking down a leakage source can be really frustrating.

Cheers,

PH

Powder Hound said:

I found the mat under the carpet can be quite wet even though the carpet feels like it is dry. You have to pull up the carpet to expose the mat and dry it really well. A fan helps, as does a string of hot days, fan blowing, and windows open.

Of course, it is all for naught if you can't find the leak.

One place you can try is the interface between the cabin air filter base and the body. The mount is a plastic piece that fits into an opening in the body, and if there's a leak at that point, it will allow water to leak into the passenger side footwell whenever it rains.

Other possibilities are all the door seals.

Good luck; tracking down a leakage source can be really frustrating.

Cheers,

PH

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Look under the car and examine the floor pan seals. One in each well. They are made of rubber and are brittle by now with age. Mine were so bad it let water in on rainy days.

If you have floor mats, it will create a nice area of wetness for mold smell to bloom.

So no leak in the trunk and no water/rust in the spare tire bin, but I removed a bunch of junk I've been toting around and the smell is much better. So with that I thought I had found the source, so I started getting the rest of the main cabin clean and got the mats out. I picked up the driver's mat and the smell wafted up. I felt the carpet and it's dry in areas but in others it's slightly damp. I don't see anything growing, so I guess it's underneath. We've had 5 days of rain and nothing is soaked. Now I'm going to use your advice and follow a few other threads and see where all the advice and ideas get me in regards to finding the source of the leak. I also found a trail of ants coming up the pillar on the outside in the space under the rubber seal between the outside edge of the windshield and the door frame. I'll get a picture later. I moved teh car in the hopes that they're coming up from something I parked over. Trying to avoid spraying it with water as I'm not sure where the water will end up. I also want to avoid chemicals unless they won't disperse on their own.

Thanks for the advice, it's gonna be a fun few days trying to find the source