I contacted my service center a bit ago regarding some mechanical nose that sounded to me like either a pump or perhaps a fan. It happens semi regularly, but not always. Typically when first driving out in the morning. They asked me to see if I could trigger it by putting the car in defrost mode. I tried that and I couldn't force the noise to occur. It's happened 2-3 times in the last week, and this morning it happened at a stop light so I was able to capture a few seconds of the noise on video(I wasn't able to jump out and see if it was louder outside the car.): (Apologies for the vertical orientation... I was trying to grab this quickly at a stop light) You may have to turn it up a bit to hear the noise. The phone's mic added some slight echo, which isn't actually there, but you can definitely hear a rhythmic mechanical sound that's new after about 20 months of ownership. It's not super-loud, but louder than anything I heard earlier under similar conditions (temperature, driving conditions, etc...). It sounds like it's located in the front drivers-side of the car somewhere. Please note the video was taken with the HVAC system OFF to eliminate fan noise as a source. Turning the HVAC system back on has no effect. Sounds like a pump to me If I had to guess.