During December I had a new leather interior fitted, so the fit of the seat
board against the wall panels is now very snug.
But still the howling draft pours through the right side seat board vent.
I wonder why no draft out of the left seat board vent ?
That might be the key to solving the issue !

Wow, that's a weird one, Roy.

So the draft is coming through that fine mesh that buts up against the
sidewalls, right next to the rear bucket seats? But only on the
*co-pilots* side?

There is nothing underneath that plank that should be able to direct
the air in any one direction -- it's just an open cavity beneath that
big hunk of plywood. Why the air would only come out the RIGHT
mesh/vent/opening is truly a mystery.

I suppose you could try duct taping a piece of cardboard to the bottom
side of the mesh, and go fly it? If nothing else, you'd be able to
see if (a) the draft stops, and (b) if it now pours out the LEFT
mesh/duct.

You sure that the little shroud around the bottom vent hole isn't
installed backwards, turning it into ram-air instead of venturi?

You might post this on Cherokee Chat, the Cherokee Pilots Association's
website. If someone there doesn't know the answer, it's either
unanswerable, or you truly are a pioneer in this particular problem.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"