Marvin which speed is the fan running at; low, medium, or high? At what switch positions does the fan run? I had only 'high' speed in my car and determined that the blower motor was good so I replaced the switch. Still only one speed with the new switch. There was a diode in the blower motor circuit that prevents voltage feedback when using low and medium speeds that was burned out. The low and medium circuitry is bypassed when 'high' speed is selected and the fan ran only at high speed.
1998 Tradewinds 7370, Freightliner, Caterpillar