msunickb,
Your "Resistor Pack" which controls the fan blower motor is burned out. The blower motor only has one speed (high) and to control the speed, there are a series of resistors that reduce current to the blower motor depending on where the selector switch is set. When the Resistor Pack burns out, you're left with one speed - "HIGH"
I'm not sure where the Resistors are in your car but usually, they're found somewhere in the heating/cooling ductwork.
Go to a Ford dealer and have them look it up on MicroFiche, they can even print it for you and it'll show you exactly where the part is located.
I replaced one recently on a Grand Marquis, I think it's about a $30 part!
Phil
