1992 Buick Park Avenue BLower Motor

Ok. Ive replaced the blower motor. The blower motor relay and the Blower motor switch. And still not working. All fuses are good. The motor does not run at all and from time to time the lights go out on my control for heat and a/c. Is it the blower motor resistor or can the electronic control unit for the heat and a/c keep it from working even though the switch is seperate. Like I said. The lights on the unit quit working at times and when it does. The doors for the heater box dont seem to move much. Do I have a wiring problem or is it the actual control unit?