WARNING: This page is about a different car, the 2006 Dodge Magnum, 2006 Dodge Charger, and 2006 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes
(C66) MODE DOOR COMMON DRIVER CIRCUIT / (C55) LEFT BLEND DOOR COMMON DRIVER CIRCUIT / (C68) RECIRCULATION DOOR COMMON DRIVER CIRCUIT SHORTED TO VOLTAGE