Late 2017 Model S 75 with the base stereo and recently started experiencing a "crackling" sound from the driver's side windshield pillar speaker (like bad AM reception), when the AC/fan is running but the sound is off! Really weird. It will go for a few seconds then stop. Tried to record it but no luck. Tried switching fan off and on, sound off and on, can't figure out any pattern. It did just come out of service for a AP 2.5 to FSD computer upgrade (I'm still on MCU1). I don't remember hearing it before the upgrade. Anybody experience something similar?