Hi guys. Try something out for me: Sit in your car, plugged in, and parked in the garage (I did this at 51 degF). Pause the audio so it's quiet in the cabin. Turn on the climate control with the fan set to 1. (In my case, I've got the blower directed to the windshield only, temp at 72 degF, Auto for recirc, and Auto for A/C, but don't think these settings matter. In fact, not even sure the fan at 1 matters). As the climate control starts up, do you hear that sound that sounds a bit like a faint, muffled compressor that slowly steps up to a higher frequency every 5 seconds or so? Question 1: What is that? I'm guessing the compressor? It is *not* the fan blower, because it steps back down and goes off (or to a very low level) after a moment, even with the fan at a constant speed. Is it the heat pump compressor? I'm surprised that it seems to step back down and go away fairly quickly. Question 2: As the compressor (as I'm calling it) begins its slow ramp-up, there is one "step" that it reaches that causes a large amount of buffeting/vibration in the cabin--very likely due to the fact that the cabin is sealed so well. Does anyone else hear this sound or is mine abnormal? Thanks for the input!