HVAC Air Conditioning recirculate mode issues

I'm not sure if my problem is already answered here:
http://www.automotiveforums.com/vbulletin/showthread.php?t=734886

So I will elaborate.

When accelerating either mildly, briskly, or even at speed with torque converter lock-up the door that shuts out the outside air(recirculate mode) will slowly close and then close all the way. I have confirmed this while my wife drove the car today and I watched the door close. At speed you only need to barely touch the gas and the door will start to close. What this causes is for the air conditioning to not feel as cold to me!

I wonder if it is the hose routing in the engine compartment or the small diaphragm that opens and closes the door itself? Any one know what the real name of this thing is?
http://img137.imageshack.us/img137/9545/p1000324qi5.th.jpg (http://img137.imageshack.us/my.php?image=p1000324qi5.jpg)

I don't want to force the door closed all the time as I need the outside air for defrost. Anybody with a FSM have the technical name for the black circle thingy in the picture?

Am I even on the right track?:screwy: