But it turns out a lot can go wrong if you leave your dryer running unsupervised. 01 of 06 Mechanical Failures Credit: tonefotografia / Getty Images Anything could happen to your dryer while you’re away, and mechanical malfunctions can escalate quickly. 03 of 06 Water Damage Risk Credit: Carlina Teteris / Getty Images You might not associate your dryer with water, but they are actually closely related. “If the dryer is left running while you’re away, this can go unnoticed and later cause water damage, mold, and ultimately expensive repairs,” she says. “If it accumulates in the lint trap, exhaust vent, or around the heating element, it can ignite from the heat of the dryer.” “Lint is fuel,” adds Godynuk.