I was wondering if anyone else has heard a short whistling sound from there trucks about 5 seconds after it is started. It sounds like it comes from the dash on the left side of the gauges. It only last about a second or two. It doesn't do it every time but it seams to to occur every time after the truck a sat for a few hours.
I'm going to take it in the first chance I get but I thought some of you might have an idea what it might be.

Thanks in advance for any insight.

I attached a very short video of my strange noise coming from the dash of my KR. It is the short whistle sound that last maybe a second. It seams to come from the area of the driver's side A/C vent. It only does on start-up and only after it has sat for a while.