Kill mold with tea tree oil. Mix 1 teaspoon of tea tree oil per 1 cup of water. Spray onto the surface with mold and allow to dry, do not rinse. This will kill the mold spores without creating harsh chemical fumes as other cleaners, such as bleach.
Once a month, add a cup of Distilled White Vinegar & 1 Cup of Baking Soda directly into the drum and use HOT water for washing. Then, add about ½ cup of vinegar into the fabric softener compartment and ½ cup of baking soda into the detergent compartment.