I have a 2001 Pathinder, it was purchsed new. Ever since we have owned it, we have noticed a foul/musty smell from the vents when the A/C is first started during the hot summer months. It does dissappear after about 5-10 minutes. I have heard that the design of the HVAC system does not allow water to adequately drain from the evaporator (not quite sure if i have the correct part). The excess moisture over time supposedly causes mold and it is the mold that creates the odor. I have had some luck spraying about a half a can of lysol down through the intake vents at the base of the windshield while running the A/C on high, but it seem to be a very short term fix. When I first mentioned it to the dealer, they said it was the in-cabin filter and charged me $90 - they claim they do not know anything about it, so i gave up. The smell is starting to come back, does anyone have any ideas thoughts or similar problems?

 

the filter is behind the glove box