Scott,

 

To keep your hand warmer and still allow the plane to circulate air; go to your favorite auto stereo sales, installation shop and pick up one of those black round 4 inch speaker grills for free.  They have tons of them when they install upgrade after market speakers in autos.  They usually throw them in a junk box or discard them.  Mount it on the hat shelf in back or on the aft bulkhead.  That will stop the air from flowing directly to your hand up the tube and the air will mix and disburse without a concentrated cold blast on your hand.

 

Bob Smiley

N94RJ