Buzzing sound

First things that come to mind....

Possibly the AC "equalizing" after the motor is shut off... remember the AC compressor is going to run in any heater position that blows air on glass...

Possibly a vacuum leak.... there will be a vacuum storage cannister of some sort under the hood... The motor might keep up with a smallish vacuum leak but it can still make enough sound (usually either a "hiss" or perhaps a "reedy" sound depending on the nature of any leak) to be heard as it normalizes across the system...

First things that come to mind....

Possibly the AC "equalizing" after the motor is shut off... remember the AC compressor is going to run in any heater position that blows air on glass...

Possibly a vacuum leak.... there will be a vacuum storage cannister of some sort under the hood... The motor might keep up with a smallish vacuum leak but it can still make enough sound (usually either a "hiss" or perhaps a "reedy" sound depending on the nature of any leak) to be heard as it normalizes across the system...

high-pitched whine that lasts for 1 or 2 seconds, then dies. Car has an aftermarket stereo, but I don't know why that would matter, except that there is still electricity in the "system"...

Any chance that you got one of those big-arse aftermarket stereo capacitors in there that is holding a charge for 1 or 2 seconds?

Is the heater/air fan always on when the ignition is? Is there a leaf in the squirrel cage?

Hey guys, thank you for the input.

I never looked at the heater fan position. That is an easy thing to check. Thanks. Yeah, the stereo is more than stock - I dunno what it is cause the last guy put it in.

But I think Jim might have it... it does kina go "reedy".... almost like it's exhaling.

The car needs to go back to Ford for some minor safety work, so I'll have them look at it.

Thank you all.

Brad