I think it is a fine idea. In fact, I think there is a similar product or a TSB from BMW for the a/c odor. It's basically a deodorizer like what you're using.

The problem is caused by accumulated water that is allowed to stand which can grow smell producing mold. Nice thought, no? One solution is to turn off the a/c a few minutes before you get to your destination to allow the water to be used up or evacuated so none is left standing.

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