Condensation in the heater case may cause a musty odor from the heating, ventilation and AC (HVAC) system after sitting for two hours or more. Our technicians tell us that a cleaner is available for the heater case and the drain system should be checked for debris.Google+
Car Problem Reports
Volkswagen Jetta TDI Odor from HVAC vents
Volkswagen Jetta TDI Problem
Average Mileage: 38,500 mi (10,000 mi - 70,000 mi)
Visitor, 2010 Volkswagen Jetta TDI, 42,000 mi
A musty odor coming from the air conditioner vents. Dealer offered to check it for a price, we decline and bought a new AC filter from auto parts store, which I will replace myself.
Visitor, 2006 Volkswagen Jetta TDI, 70,000 mi
I have begun to notice a distinct smell of antifreeze in the car, especially when climbing mountain ranges. The smell emanates from the vents even if the fan is completely turned off. No solution yet, but I suspect a slight leak in the heater core or the attached hoses. It resulted in extremely lungs for several weeks after an 8 hour road trip.
I have noticed when I started using the AC in the Spring now, AC smells like mold. After leaving the fan on high for a few minutes, the smell disappears (and or i'm just getting used to it).