I have a Kenmore Classic Grille Downdraft Range. Sometimes the fan is coming on while we are baking. If I turn it on Broil, and then reset it to Bake, the fan will stop for a little bit. It doesn't always happen, but the longer we cook, or the hotter the oven, the more likely it is to happen. There aren't any F codes on the control board. I have replaced the thermostat once since I've had it, and the control board a few times, but never experienced this symptom before. Any suggestions would be appreciated.