How to prevent mold inside 996 convertible?

*Sorry, not a "technical" question per se, but lots of 996 people here...hoping someone might have a solution. My 2002 996 is parked outside on a slightly sloped driveway. Climate-wise I'm in Oakland, California, and the car is typically in the shade until 2pm...when it finally gets some afternoon sun. The problem is, during the winter rainy season, the car just seems to be water logged. The convertible top saturates when it rains or even due to the overnight marine layer, and the moisture just never leaves the car: The inside windows are covered in condensation at all times, but the big issue is I get mold on the headliner and even parts of the seats. I did put a tub of Damp Rid in last year (hard to say if it did anything), but I just wanted to see if this is normal...or if there's anything I can do to help remedy the situation? Thanks in advance for your thoughts- RT

Stating the obvious but try to get the car under cover. Next, you need to restore the water repellent on the top. 303 and other companies make good products. The water should bead up and roll off. Watch this for potential solutions to your interior situation. You could have clogged drains which are allowing water to get in the interior. https://m.youtube.com/watch?v=pn5Nfmyz61s

Thanks for the quick reply. No garage, and I actually did use 303 when I first got it, but I think the clogged drains diagnosis is almost certainly the culprit. Even when sunny out for days after getting wet, there's clearly still moisture in it...so I have to think this is the issue. I also wondered if the fact that it's on a slight slope is adversely affecting its ability to drain. I've already found a few good sites with info on drain locations (I'm sure those will be fun to get to), but this would certainly explain the water not leaving the car. Certainly open to any other ideas, but this is a great start...thanks again.

Keep the roof up and the drains clear... shouldn�t be a problem

+1 for cleaning all the drains, including the space behind the rear speakers, the rear wheel well drains, and the groove where the clamshell meets the body. Make sure its dry under the rear floor carpet. Spray an extra layer of convertible top waterproofing spray on the canvas until water beads up on the roof. https://rennlist.com/forums/996-foru...ar-drains.html https://rennlist.com/forums/996-foru...er-drains.html

Not sure if you have shore power to the car, but I use a gun safe dehumidifier in the winter when my car is parked for weeks. You may want an RV style one. The gun safe one works great for my car, but is parked in a carport and not open to the elements as much as yours, but it may help. Amazon.com: LOCKDOWN GunSaver Dehumidifier with Slim, Low Profile Design, Easy Installation and Simple Operation for Vault Humidity Control and Rust Prevention : Home & Kitchen Amazon.com: LOCKDOWN GunSaver Dehumidifier with Slim, Low Profile Design, Easy Installation and Simple Operation for Vault Humidity Control and Rust Prevention : Home & Kitchen RV: Amazon.com - Caframo Limited 9406CAABX Stor-Dry 9406 Dehumidifier, Warm Air Circulator Fan, Small, Metallic - Clothes Dryer Replacement Parts Amazon.com - Caframo Limited 9406CAABX Stor-Dry 9406 Dehumidifier, Warm Air Circulator Fan, Small, Metallic - Clothes Dryer Replacement Parts Hope that helps, Nick

I drive a convertible in Oregon ，because I make good choices and as is inevitably always the case I have a couple minor leaks. The intrusion is enough to fog up the interior windows.The musty smell awaited me. It was even worse on hot summer days. A professional car cleaning company wanted around $500 to sanitize the vehicle.So I put the dehumidify(which brand? Full introduction here https://cardehumidifiers.com/car-moisture-absorbers/ ) in it to see if that would help. The musty odor is gone! I am going to put one of these in all my cars. I highly recommend dehumidify for use in a car that sits an extended period of time.

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When you take off the interior side panels by the rear seats, and the panel across the rear, you can see the entire drainage system. If you pour water in there you might see that even a partially blocked drain to the wheel well could cause overflow that would go down under the seat and to the foot well. That could be exacerbated by a slight upward slope or downward slope, as the drainage tray would overflow earlier. A steeper upward slope, however, should result in more water going to the rear drain. If you can't find the specific source or even where there may be water sitting, it it could be the roof. You may need to protect it more often, but if it's going to be wet more often than dry and you can't keep it waterproofed, that's a challenge that may require one of the additional steps like the dehumidifier, or a new roof. I would start by looking at all the drains, front sides and rear. It gives you the opportunity to find any really damp spots and take some extra effort to start with a dry car. If the footwells are damp in the rear, take the seats and carpet out, pull the plugs and look in the cavity under the seat too. After I found my problem, I was puzzled as to why it still got wet. There was still a litre or so of water in the cavity, sloshing out on to the carpet. Then give the roof a good cleaning an protecting. Go to another state and find some sunshine for a few consecutive days...

Trust me when I say this. Your car most likely smells like mold/mildew because the drains are clogged and water is being left sitting somewhere. I suspect your back seats and floorboards are soaked. Take a look at my video series on this topic and how I cleaned out the drains AFTER the car was left for YEARS to sit in water.

Good advice above about the rear drains and mold. My 996 was garaged in Florida but the mold continued until I finally cleared the drains. /X3

My 2003 996.2 cabrio recently had the driver window regulator replaced as the old one was not functional. The following week I washed the car, and opened the door after to find a TON of water in the driver side rear footwell. I assumed the higher pressure from the hose was enough to overwhelm a partially clogged drain as I had never had this problem before. So I dried it out... then it rained 48 hrs later and the same thing happened. I took it in to get it checked (and professionally dried out) and the found that the culprit was the seal where the window meets the body. I suspect the window sits differently against the seal now that the regulator is fixed, and the old seal had formed after many years into an abnormal shape. Hopefully the new seal fixes the issue... but it's still at the shop. All that to say- I unfortunately found yet another way to get water in the car.