2002 Escalade-cool air coming in

I have a 2002 Escalade that I just love.  On a recent trip we noticed (now that it is winter)   that there is cool air coming in on the passenger size just below the glove box in the area of the fans/cowling etc for the heating and cooling.  Took it to the repair shop and they could not find anything out of place without tearing the area apart.  Any ideas?
 
Thanks
 
Neil Melby
South Dakota