Outdoor HVAC unit making sounds

To start, I live in Virginia and we just got a bunch of snow, but mostly ice. It hasn't really gotten above freezing in many days now. At the time of writing, it is currently 11 degrees. I woke up to a sound coming from my hvac unit that could best be described as a "whirring sound" maybe? However, it only does this for a little bit, and then it stops. Is this normal? I've only owned a house for a year so I'm not 100% sure if this is normal because it's cold or if I should call an HVAC person.