In our lab when we need to decon (from bacteria, yeast, mold, fungi) an instrument such as an humidified incubator or a BL2 hood. We've use a company that will peroxide gas the unit. Takes a few hours to seal, gas and to neutralize. Wouldn't know if its ever been done with a vehicle.
But in the same idea as mentioned in Chapman's and PT's post, perhaps you could spray in the "cleaner" with the air vent open and then run it for a while with air in recycle mode.
I've got an ozone generator that will render anything left over pretty much inert, but in order to do that, I have to get most of the trim out. Ozone will turn polymers into dust very quickly in the concentrations needed to kill off all the leftovers.
It won't hurt my Teflon-insulated wires, but I'll have to wrap the connectors because nylon would be absolutely destroyed. Seems to me Weatherpack might have considered HDPE connector housings rather than nylon. It won't hurt the climate control system, as that's HDPE. Of course, that foam in there will be dusted, but that happens over time anyway.
You have to be careful with this stuff. It's dangerous and destructive; but that's why it works so well.
Spraying with hydrogen peroxide and leaving a borax film around finishes the job.
Most of what's available on the market to kill mildew and mold doesn't actually do very well, and a lot of times, even commercial operations are really just fucking you over, in the end. Once this stuff really gets into a car, there's only one way to reset the system, and that's to pull it apart and murder the fuck out of it.
Vaporized hydrogen peroxide, though; that's a different story. That works very well. It's much safer than ozone, but more difficult to arrange. I've already got an ozone machine that I plug into a socket and turn a couple of dials. It's pretty simple.
I could build a system to vaporize and distribute hydrogen peroxide or hire someone with the setup, but either way I'll have the other shit done before that's sorted. If I build something, I've still got to concentrate the solution. I don't know about hiring someone. It might be fast and easy, or might be slow and expensive.
Cheers,
Kennith