Fixing the Air Conditioner, Defrost, or Car Vent Smell
Douglas Miske sent us an article by Cam McRae of the Toronto Star with advice on curing the a/c smell. Dealers can eliminate the bacteria and other growths which cause the smell by using a disinfectant; holes may be drilled to get to hard to reach areas. Do-it-yourselfers can save about $50 by buying Fresh Air from many department stores - it costs $15 (Canadian). Wynn's also sells a spray.
David Ta wrote: The evaporator design having horizontal fins is the root cause of the AC musty/stench smell on first startup, which will fade out in a good few minutes. ... the real cure is to install an OEM evaporator having vertical fins to drain off the condensation, IF there is such one in the aftermarket for any model having this problem. Or you can modify your car to allow water shedding off easily. An old colleague in the office confirmed that he got this problem with all his recent cars, including Chevy, Ford, Chrysler. Every year, he mixes water and baking soda and poured it into the drain area next to the firewall, rinsing it later with a water hose.
Another option: dry up the evaporator, after every AC use, or at least daily before turning off the ignition, by simply turning up the temperature to full hot, at maximum speed, while selecting "Front Defrost" for a few minutes. You may not like this inconvenience, but comparing to that when a new evaporator is required, and the evap is out of warranty, plus the musty smell every time the "Front Defrost" is selected, I think the inconvenience is justified. (Defrost activates the air conditioner compressor on most cars). This seemed to work for me.