I have been experiencing some intermittent noise emanating from the driver's side dash closest to the center of the car. I have tried turning off the climate control system and radio but the noise persists. It occurs while driving and when stopped. It sounds like clicking with about a half second frequency.
I have not yet taken it in due to its intermittent behavior.
The noise began last year when the vehicle had about 72,000 miles. It now has 77,000.
Having the same problem with my 2007 Expedition EL EB 4x4 with 159,000 miles. Seems to have something to do with AC, however I do hear it even with the AC turned off as well as if I turn the AC off while it's making the clicking noise. Maybe something to do with the fan that draws in outside air? I'm pulling at strings as well as pulling my hair out some days with that clicking noise. Did you ever find a solution to yours?