Musty smell in cabin from air vents

[cnavarro]

I've noticed a musty, maybe mildewy smell from the vents when i've used the a/c previously and parked the car after the a/c was used. Example, I drove a week ago and it was rainy and I used the a/c because it was very hot and humid. Fast forward one week. Last night I get in and start the car and the smell is horrendous. It took a few minutes with the a/c on again and the windows down for the smell to go away. Is there maybe a drain somewhere that is blocking up?

[tonythetarga]

Mold spores are everywhere and, no doubt, in your ductwork. While using the air, the ducts get cold. When you shut off the car, the ducts warm up and may form some condensation inside the ducts and just enough moisture to urge the mold to grow and emit more spores. Fast forward as you say, and by turning on the airflow you sent the spores airborne within the car and up your nose.
This happens in almost all cars and many new cars have HEPA filters in the cabin system to trap them before they become airborne.
One thing to consider is to turn off the air for the last 5 minutes of your drive and before you turn off the car. Turn the temp all the way warm and leave the blower on to circulate warm ambient air. It will warm up the duct and not allow any condensate to form when you shut it off.

[silverc4s]

Charles,
This is pretty common in M-B & BMW sedans. The dealers have a spray that can be used through the vents while operating to do a pretty good cleaning.
If your car has any filters they should be OUT while this is being done, then cleaned or renewed. Pretty standard deal here in humid old Texas.

[Wavey]

Charles,

Wurth makes an excellent HVAC system cleaner, "Air Conditioning & Heathing System Treatment" Haven't used it in the Carrera, but I recently used it in my wife's Saab. In that case I removed the cabin air filter and sprayed it directly into the running fan, and switched through every possible Heat/AC/Vent combination. The car had a mouse nest in the fresh air intake, and this completely removed any remaining odors. If our host doesn't carry this, it's available from

http://superiorcarcare.net/wurth.html?gclid=CPyB7v2Zz4cCFQt9VAodpxsjMw

[tcar]

Frigi-fresh. Napa has it.

[cnavarro]

Is there a filter on a 91 or even better, where would be the best access point to introduce the cleaner?

I actually tried turning the a/c off last night a good 5 min before turning off the a/c, so we'll see if that's any better when I go to drive it later today.

[Wavey]

Not sure about the 964, but in the earlier cars the evaporator and fan is in the smuggler's box.

[randywebb]

IT would be BEST to tear the whole thing out and clean it all up - and bleach the mold colonies. Wear a mask/ventilator and some skin protection to be really safe.

Barring that, I'd use the best of the flow-thru cleaners.

Some species of mold can be extreme health hazards. I would be really careful - people don't think much about it, but to me (a biologist who dislikes being a substrate for something else to grow on) parasites can be more dangerous than chemical exposures. Chemicals are not out to get you & mold is. My doctoral advisor had his eyeball eaten out by a mold.

Around here, people periodically burn down mold infected houses. It's that bad. The Univ. basketball coach burned down his multi-million $$ house a few years ago.

That's why I advise a very thorough cleaning.

[Wavey]

OK, then here's a solution, no mold guaranteed

[randywebb]

hahahaha

but... some spores will get released in the air plume before they burn

a small tactical nuke WILL do it tho -- BTW, DoD has studied that as a way to decontaminate a battlefield that has biological or chemical agents on it -- instead of NBC, sorta N vs. BC

do you live inside the city? I'm surprised mice got in unless you are in an exurb.

[CliffBrown]

Charles

I agree with the bleach to clean out the mildew & mold and also make sure the evaporator drain is clear and working very well.

[cnavarro]

Ok, I ran the ventilation system at full and sprayed a bleach/water solution in the air intake on the hood and did enough that it was coming out the drain on the bottom. It most definately smells bleachy inside.

I did make one observation - when the a/c is on, the flap at the intake is almost completely blocked off and no where the amount of volume is going in there, even with the recirculate off.

Which leads me to another question. Where is the intake when the system is on recirculate?

Also, is there somewhere else the air is being drawn in?

[defcon65]

I've had luck cleaning that smell out by running Lysol through the fresh air intake followed by Ozium. You'll want to remove the vents if possible and catch what comes out with paper towels or have an assistant operating a wet-vac on the inside to reduce the mess. The only way to get rid of it completely is a thorough disassembly and cleaning as Randy noted. If you decide to take it apart, make sure to take pictures and notes of what goes where - there are dozens of different fasteners, clips and hardware to contend with once you get into it. It is a task.
This usually happens when the condensate drain gets clogged for some reason.
Careful using the bleach, it will react with any aluminum it contacts, not to mention damage leather, carpet, etc.

Regards,

[futuresoptions]

There is a product call BIOFRESH can be purchased at most residential A/C supply houses. If not they can probably order it for you. This product should be atomized into the air with your a/c on recirc. This product is also very good for your residence. This product will kill mold, and should help clean up the smell and prevent reoccurance for a while. Especially good if you have allergies or live in humid climate or if you haven't had your residential unit serviced in a while. Try it guys it usually does the trick. A low cost solution is to mix bleach and vinegar in a bowl and sit it on the floorboard while you have a/c on recirc. would not recommend staying in the car for that one, but they say the BIOFRESH is safe to be around.

[cnavarro]

After putting the bleach solution in mist through the fresh air intake on the hood with the a/c on high, the smell was entirely gone, even days later.

Just to be on the safe side, I purchased the professional product from Napa and applied it into the recirculated intake - which is right in the center of the dash underneath, behind the center tunnel controls. We'll see how long it lasts.

I also normally put in tubs of damp rid in the car every time I park, to get any moisture out of the air.

[moparlou]

I have had this 2003 911 convertible for about 2 years and the musty smell doesn't go away when ever I let the car sit.
I noticed the AC damper activator box wasn't working so I removed it. To do this I had to pull up the passenger carpet to get room to work.
Well, the carpet in the passenger has a backing sponge about to 3 inches thick. It was soaked. I has been for years, even from the previous owner. The carpet is tight and doesn't breathe. I remover the passenger floor carpet, pulled all of the wet sponge from the back of the carpet, all of which had the smell that I have been smelling. I dried and deodorized the floor pan. I am keeping this piece of carpet removable for future inspection, and I am putting in new "carpet padding".
The reason everyone thinks it is the AC evap is because the smelly carpet is directly below the AC inlet.
The small damper actuator has a flaw of a broken drive gear that cracks over time, and the outside door and inside flap go out of sync, and the drive gear clicks because its spline shaft is twisting in the hub of the gear. The number of the box is an audi number 1 J1 907 511A ($25). You wont find this number anywhere. Im glad the box failed or I would still be looking for the smell.
I slit the driver carpet and felt under, but it was dry.
So believe it or not, this water logged sponge would never have dried out and all of the sprays, flushes and air movement would not solve the odor because it isn't in the airbox.