During the heating cycle of my hvac unit, a loud hum comes from the unit outside. It happens periodically and typically starts loud, then slowly becomes quiet. Then the fan kicks on. The house is heated and cycles appear to occur when needed. Is this normal... the noise wakes me up as the unit is located outside my bedroom.

Locating a unit right outside a bedroom is a mistake but sometimes there is just no other place to install it. With a heat pump also comes the defrost cycle and that can be a bit loud. Start up can also create some noise so it is possible you are hearing the unit operate. Your options are to have the unit professionally checked to be sure its operation is with bounds performance and noise acceptance wise and to consider moving the unit to another location away from your bedroom.

Thank you. It's a new unit with a new home. It functions as it should and has always done this during the heating cycle. I appreciate the feedback! Thank goodness I live in FL and the heat doesn't kick on that often. :-)