94 Blower motor resistor

I have a 94 exp. 4.0, that will eat a blower motor resistor up in about 3 days. I know there has to be a short somewhere but have not had time to track it. Any ideas where to start? Could the blower itself cause it? (Replaced blower about 90 days ago but had not replaced a bad resistor untill recently). Thanks for any help you can offer.