When van under speed, fresh air gets rammed in through intake snorkel
behind upper grill (exterior) and two flaps in the heater/fresh air
box get blown open. If heat control valve is open, and appropriate
flaps open, you will feel the heat even with fan off. If foam on all
flaps is ok, and control cables are working right, (and IIRC) you
should be able to shut off the flow of fresh air to all outlets.

Of course the easy solution is to turn the heat down or off. Assuming
the heat control cable and valve are ok.

Speaking of grilles, are the grilles secure? Not likely they'd be
flapping in the wind, but you never know.

Neil.

On Mon, May 5, 2008 at 8:21 AM, Neil2 <vidublu@gmail.com> wrote:
> Hi volks,
>
>  This weekend I noticed a vibration noise up front that I've never had.  It
>  only occurs at about 50 and higher speeds and sounds like its in the dash
>  or behind the grill, possibly.  I've driven me van plenty of times at that
>  speed but have never heard it before.  I replaced the dash a few weeks ago
>  but am sure I've had it to that speed since as well.  I may have caused it
>  while adjusting the vents.  Before I noticed the sound I felt warm air
>  blowing thru the two dash vents (defoggers) on the dash top near the
>  windshield and down on me feet so tried to stop the warm air flow.  I'm sure
>  this warm air has been flowing all spring but it's just now warm enough to
>  bother me.
>
>  Does anyone know of any kind of vent flapper noise at these speeds?
>
>  Thanks!
>
>  --
>  Neil
>  '82 Diesel Westy
>  Me other car is Swedish
>

--
Neil Nicholson. 1981 Air Cooled Westfalia - "Jaco"

http://web.mac.com/tubaneil
http://tubaneil.googlepages.com/