Possible Causes

WARNING: This page is about a different car, the 2002 Mercury Villager. However, it is still accessible from the selected car via links, so may be relevant.

Central Junction Box (CJB) fuse No. 37 (10-amp).
Central Junction Box (CJB) fuse No. 45 (15-amp).
Central Junction Box (CJB) fuse No. 47 (15-amp).
Blower motor relay.
Rear blower motor.
Rear blower motor switch (front).
Open/Short circuit.