Attic ventilator fan fire. Squirrels commonly use these fans to enter attics. The screen that is inside these units are ony designed to keep out leaves. When Squirrels make their entry they bend down the screen which then blocks the blades from turning. The fan blades jam and the motor overheats and a fire results. In this case the heat was so intense it melted a metal blade. Sparks which dropped from the fan caused a fire in the attic causing major damage to the home.