Weird Noise; Help, Please.

[HRP]

Car: 2002 LS430, only options are heated seats and sunroof. 53k

Today while pulling into a parking lot my wife and I heard a faint high pitched continuous with slight pulsations noise which seemed to originate from behind the dashboard on the right (passenger) side. It came and went, persisted with the car stopped, placed in park, and the climate control off. Emergency brake was not accidentally partially engaged. No idiot lights were on. All windows up. Radio off, cruise off. Turned off the ignition and withdrew the key. The steering wheel moved to its off position. The noise persisted for at least 15 seconds then stopped. Shopped for a few minutes. Started the car, the noise returned and continued intermittantly as I drove 4 miles home. Stopped as I pulled into the driveway. The noise was pitched at about an A above high C (I'm a barbershop singer, so checked it as remembered with my pitchpipe.) We had been stop and go driving, running errands prior to our last stop. total milage on trip around 25. Anybody got any ideas as to the cause? I suspected a foreign body in the fan, but with the ignition and climate control off?

[jainla]

I know the LS climate control system uses mylar flaps instead of conventional plastic flaps.

Is the system set to run on auto or are you specifying fan/vent settings? Perhaps one of the motors running the airflow handlers is slipping or something? Sounds odd though that it runs so long after the CC shuts down (I can hear the handler run for about 5 seconds after I turn my car off).

The other thing I know is that the air filter for the passenger cabin is behind the glovebox on the passenger side; maybe it's loose or not fitting properly and air is bleeding through it somehow? Try opening the windows (will make it harder to hear I know) and see if it goes away?

Good luck....keep us posted