I have a99 Concorde LXi. Car runs fantastic but now have small problem. The heater A/C fan does not change speed. I have checked fuses under dash and under hood. I have pulled glove compartment out and heater control facia. I can hear flapper doors opening and closing while changing from heat to A/C and increasing/decreasing temp. Also the small rotary "Fan"? behind the fan speed switch spins. Any help would be appreciated as to what part needs to be replaced and how / where to test it.

 

If you have automatic temp control, the fan module probably needs replacing. If you don't have ATC, then it's the resistor block. Your description of the little fan in the control head leads me to believe you have ATC.