1995 buick roadmaster/heater and ac fan staying on

There is a module that controls the motor located arend the blower moter that will need to be replaced. Not sure if this is available other than dealer. check with auto parts stores first. I would ask for blower motor control module.If this helps please reply and good luck

I've owned many of these cars and have seen this problem before. The answer is twofold. Replacing the blower control module may cure the problem temporarily. But is likely that your blower motor is drawing too much current through the module due to age and a worn bearing in the motor. If you replace only the module, it will probably fail again. Do 'em both and be happy. Good luck.
Dave D.