The personal auto policy will pay for direct and accidental loss to the insured's covered auto and its equipment. What you have described is a direct loss since the filter of the car has been actually physically damaged by the mold. As for accidental, that is interpreted from the insured's viewpoint, and so long as the insured did not know there was mold growing before the damage occurred then it is an accidental incident from the insured's point of view. So, the terms of the insuring agreement have been met.

And, none of the policy's exclusions apply. There is no mold exclusion, and the wear and tear exclusion is for the normal aging of a car from its use. In this case, the loss was the result of moisture and mold. Even though mold grows over a period of time, this was not the normal aging process of the car itself. So, the claim should be covered so long as the insured has other than collision coverage.