Exterior tempature reading

On my 2007 five hundred, I usually don't use the dual function mode on the A/C-heater. In the "single" mode the temp setting would show on the left side of the window and the external temp would show on the right side, instead of the passenger temp setting.
I recently used the dual function, by pressing the "dual" button, and when I went back to single mode the exterior temp no longer appears. I can hit the EXT button and toggle back and forth between temp setting and ext temp but it will not display both as it used to do. Is there a "trick" to getting both to display at the same time?

Thanks,
Larry

My recollection is that the ext temp never shows at the same time as the interior selections.

Exactly.