Possible Causes

WARNING: This page is about a different car, the 2003 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

An open in circuit 29-FA10 (OG/GN), 20-FA10 (PK/OG) or 31-FA10 (BK).
DATC module.

Fig 1: Pinpoint Test A: No Communication With The Dual Automatic Temperature Control (DATC) Module (Steps A1-A4)

Courtesy of FORD MOTOR CO.

Fig 2: Pinpoint Test A: No Communication With The Dual Automatic Temperature Control (DATC) Module (Steps A5)

Courtesy of FORD MOTOR CO.