The convection fan will turn on once the oven reaches the set temperature. When it needs to fire the burners to heat up again to maintain temperature, the fan turns off. It will turn back on when the burner stops. The fan is very quiet - I can't hear it - but if you turn on the oven light and look at the back wall of the oven, you can see the fan blade(s) when it is not spinning (while the burners are firing) and will see that it is spinning when the burners are off.