I had that in one of the previous update. it drained for 3-4 days, then stopped doing it on its own.
i thought it's the computer configurating and calibrating the settings.
not sure, just a guess
had the same thing happen to me yesterday too!
I assumed it was the fan cooling the cabin but it wasnt really hot enough inside. After opening the door it switched on the AC. After closing the door immediately all noise was gone.