I'm talking about the control unit that is in the dash, where you turn on your heat, a/c, adjust the temperature, blower, etc. If I remember correctly, you can remove the dash bezel and the guages above the control to see the top of the unit. There was a wiring harness that attaches to the top that was left off on mine. The low speed blower always works no matter what, but without that harness attached no other speeds will work. Hope this helps.