Blower Motor Circuit
WARNING: This page is about a different car, the 1999 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.
Blower motor speed is determined by changing current flow to blower motor using resistors. Blower motor switch has 4 speeds that are obtained using 3 resistors that are wired in series. Heater blower motor switch resistor is wired into blower motor ground circuit.