[coolwhip]

On my 2018 Venice I just found that when I tried to get fresh unheated air through the vents, I get very hot air regardless of the push/pull knob position.
Until recently I didn't turn on the fan for cooling.  When I rarely used it, it was for heat, so I don't know how long it has been this way.  From the feel of it, the push/pull knob seems to be operating the diverter door.
It's been quite a while since I've been under the cowel and seen the trap door which is supposed to open/close the heat flow.  It was connected and working at that time. 
Before I dig into this again, does anyone have experience with this?

[RustyTeeth]

Know this is a older thread, others may benifit.
The panel knob does actuate the diverter door.  Door must close tightly for good heat distribution. 

In the open position, seems it just lets cabin air in, that mixes with heated air. Not  really a cool air blower. 

Will look into it and see if it can be tuned up. Pun intended

[coolwhip]

I dug into mine a little further.  I remembered wrong, the vent trap door is accessible from the cab above the passenger knees, not under the cowl.  I can see my problem.  When I push the knob in to shut the vent (to shut off heat) it closes, then bounces back a little - thus letting in heat.  You need to be a contortionist to get to the screw to try to reset the position of the closure connection on the push wire.  My simple solution to completely shut off heat for the summer is to push a small block of hard foam in the hole to force the door shut.  Don't block the fresh air vent hole, which draws air from the cab, with too large piece of foam.  Not a very permanent fix, but it works!

[RustyTeeth]

The cable flex and slack also plays into it, was going to post pix but I see yours now. it seems it just allows interior cabin air to mix with the heated???

Must be a way to get a ram air in there!