Help, Advice, Owners' Discussion and DIY Tutorials devoted to the second generation C70, S40 and V50 Volvos -- awkwardly model year 2004 ½ onwards -- plus where to go for advice and discussion on Volvo's sporty C30 Coupe powered by Volvo's ubiquitous inline 5-cylinder power plant.
I got that moldy smells rom AC some have. The smell only appears after rain, or on humid climate, and comes from the vents.
Here what I did to solve it, none of this worked.
Remove cabin filter, and put a AC cleaning solution with disinfectant directly to the evaporator (where the cabin filter is located)
Spray the AC cleaning solution in the vent
Let the AC work for couple of minutes
Place a new cabin filter (charcoal activated)
The smeel goes away, masked by the scent. A couple days later, it comes back!!
I have also checked for water on the carpet, looking for a possible rooftop drain leak after a heavy rain. I found nothing. Anyway, the smeel is only coming from the vent, not the cabin itself.
You may do this - use the cleaning solution that you already have
Alternately, you can also engage the recirculating button and spray into the intake inside the cabin - I think it's above front passenger feet but not sure exactly where.
All these without the cabin air filter in place, but with the cover installed.
Don't use bleach, it may corrode the evaporator. Some use Lysol.
A friend used these and had pretty good results. Meguiar's Air Freshener, New Car kits. He got it online from Walmart or someplace. It looks like a bug bomb for the house. You turn the car on, put the A/C on recirc and lock the top down on the cans and close the door until they have finished. He used two of them at the same time because the car had been smoked in. I don't know if it cleans or just masks odors, or how long it'll last, but it's been a couple months and so far seems good. My V50's previous owner loved Golden Retrievers and the back area has a distinct doggy odor when the direct sun hits it. I've been using Chemical Guys New Car spray, but I may try the Meguiar's Air Freshener kit if it doesn't help long term.