I was about to order that thing, when someone recommended this (Quest odor eliminator) :
Quest/8 oz. odor eliminator (OE-1) | Odor Eliminator | AutoZone.com_.
Its sold at my local Autozone so I don't need to pay and wait for shipping.
Its effective when used in my 4Runner. The AC smells fresh, and until now, after 5 months the bad odor didn't come back.
But in my my other vehicle, which has cloth seat cover and cloth floor mats..its ineffective
Sure it killed the molds and bacterias in the AC evaporator, but the smell on the seat covers and cloth floor mats get circulated and again will contaminate the AC.
So it depends, If you are sure that the smell comes from the AC, those products are good. because it will kill the bacterias and molds in its source.