Possible Causes

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

An open in circuit 1381 (WH/LB), 1375 (PK/YE), 1376 (BK/LB) or 1126 (LB).
A short to ground circuit 1381 (WH/LB), 1375 (PK/YE), 1376 (BK/LB) or 1126 (LB).
A short to voltage circuit 1381 (WH/LB), 1375 (PK/YE), 1376 (BK/LB) or 1126 (LB).
A short together circuits 1375 (PK/YE) and 1376 (BK/LB) or 1126 (LB) and 1381 (WH/LB).
Auxiliary temperature blend door actuator.
SJB.