This could be due to an issue with your blower motor. Your blower motor is your fan, if your blower motor has debris then it can cause your heater to not work properly and for fan to make a noise. Many times we find mice and or a nest in the blower motor and that is causing the noise. If this is unaddressed for a long period of time it can cause damage to the blower motor and it will have to be replaced due to damage. Give us a call to schedule your appointment and let us take care of you.