You should hear 2 seperate sounds; one of the water movement and/or water control, and the other of the fan and fan motor. If no air is moving and you hear a moderately loud hum sound, then the fan motor is stuck ( bearings probably worn or seized) and it will do more harm to allow it to be on without the motor running. Some motors can have their bearings repaired, other motors must be replaced. There are some units that use a fanbelt from the motor to the fan blade and it is possible that the belt broke. ou need to remove the access cover (with the power off) to see for sure whether it is a motor or a belt. goodluck, Macgivor