Blower Motor Resistor
WARNING: This page is about a different car, the 2002 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
The assembly is located on evaporator housing in engine compartment. Three resistance elements are mounted on resistor board to provide 4 blower motor speeds. Depending on heater blower motor switch position, series resistance is added or bypassed in blower motor circuit to decrease or increase blower motor speed. An overheating protective device (thermal limiter) will open resistor coil circuit when temperature reaches 250°F (121°C) interrupting blower motor operation in all speeds except HI. Thermal limiter cannot be reset and is not serviceable.