when the blower stops working check for power at the blower. if there is power then it's the blower. If no power more then likely it's the resister. Resisters are more common and they melt the plug and especiall how it works better on some settings than others.
Also resisters don't usually come with blowers and are like $15-$20 new at the parts store. The last one I did I couldn't even unplug the connector it all melted into I big piece of love. Had to change teh plug end also.
FORD = F'd Over Ridiculous Design
Rims, fog light conversion, Interrior lighting recolor from starfuryt