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 F26 (65-amp).
Central Junction Box (CJB) fuse F33 (20-amp).
Central Junction Box (CJB) fuse F39 (20-amp).
Ignition switch.
Blower motor relay.
Climate control panel.
Blower motor.
Blower motor speed control.
Short or open circuit.