So, I've been dealing with a musty A/C smell and am well aware of the evaporator coil reasons and "cleaners etc. I wanted to share with you all what I found. I own a 2015 991 Turbo S cab that is about 9 months old and last week the air started smelling very musty from the vents. I took it to the dealer who advised I change the charcoal filters, and of course after doing so, the smell did not go away. So, they suggested spraying a chemical into the evaporator for killing mold etc and I made an appointment to do so next week. Anyway, I happened to notice that I didn't see any condensation drippings under my car after running the A/C and after looking at the PET diagrams, I decided to look for the drain. Also, I took the hygrometer from my cigar humidifier and checked the humidity level in the car and noticed it was about 10% higher in the car then outside so I became very suspicious. Needless to say, I couldn't find any drain.... So, I put it up on blocks to get a better view underneath. Still no drain seen. I then removed the under panel and about a pint of foul smelling liquid came out of the drain. It seems that the under-panel foam was completely obstructing the evaporator's drain. I cut away the foam, drilled a hole into the under panel and exteriorized the drain. My question is; are these car's designed to drain onto the interior side of the panel?? is this some kind of a manufacturer's error or could a tech have put the panel on too tight or wrong after my 10k service which was recently done? I cannot imagine the drain being designed like this. The foam should not be obstructing the drain. Anyway, the smell is reduced but not gone and also I live in the desert so humidity isn't an issue.

Thoughts?

The photo on the left shows the under-panel being pulled away from the drain and the foam which was obstructing it shows the mark where it was in contact with the drain. The second photo shows how I cut away the foam that was obstructing the drain.

 

Would be interested to see if other cars have the same blockage as this doesn't look right to me. Did the foam otherwise seem to be in the correct location? Just wondering if there is a chance it was placed a little too far one direction and caused the blockage because it looks like it was just an inch or so from the side of that top piece of foam.

 

I think there have been others who have experienced the clogged a/c drainage - usually from dirt and debris. Have not heard of blockage from foam. Think it is a good idea to check drainage every year. When you say underpanel, I am assuming you mean the plastic wheel cover in front of the front wheel?

 

The drain for the evaporator coil is under the passenger seat towards the midline in this car . I removed the middle under panel that exposed the drain. The drain empties into the interior surface of the panel ???? There is foam on the interior surface that I'm assuming dampens any rattle. The foam was occluding the drain .

 

Smell never went away despite replacing Evaporator coil and box. Dumping car.

 

How do you get rid of it with the smell? Isn't it kind of like that Seinfeld episode? Seriously, try a different dealer. The car is under warranty - there must be a fix.

 

I had a similar problem with a Range Rover, minus the foam.
Range Rover tried replacing the evaporator coils, and spraying a chemical in the intake filter. After three visits nothing worked.
Fourth visit and in a completely different city the RR dealer had a new fix. The installed a new drain so they can flood the coils to wash them with a cleaner, and let it drain better.
It hasn't smelled since.
I think warranty should eventually solve the issue, especially since you solved the source.

 

Isn't there supposed to be another tube going through the black grommet?