Help with a mystery sound

Hey everyone. Hope this is a place to get some help on something. Just bought a house over the summer and am in the stage of learning all the new sounds of the place. It’s a new build (7 years) so it’s quiet for the most part or I can identify the usually things.

Say for one odd noise. In the summer on the north side of my house at about 2-4am I would hear a rhythmic “thump” that almost sounds like plastic on plastic. Like a vent door, or something. I even thought it was pipes cooling, or the sprinklers. But many night of no laundry or shower or lawn sprinklers shut that down.

Now we are at our first snow of October and that same sound woke me up this morning g about 7am. It goes off like clockwork, every seven seconds and last for about 2 mins then stops.

Any ideas or advice would help. Thank you.