Anyone figure out the high pitch whistle sound when shutoff?

[JefferyGT]

Fuel vapor recovery system...

 

[Asp007]

So, this is the noise that I hear after the truck is off. I contacted the service Department from Ford and they have no idea. Anyone have any suggestions?
View attachment IMG_1033 2.mov

 

[NASSTY]

So, this is the noise that I hear after the truck is off. I contacted the service Department from Ford and they have no idea. Anyone have any suggestions?
View attachment 333261

I've seen this discussed on the F150 forum and it was the A/C hi/lo pressure equalizing.

 

[Asp007]

Excellent! Thank you