Blower Motor Resistor
WARNING: This page is about a different car, the 1998 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect blower motor resistor connector. Using an ohmmeter or a self-powered test light, check for continuity between blower motor resistor terminals. Continuity should exist between all terminals. If continuity does not exist, replace blower motor resistor.