A/C / Heater fan will not run on high. It does run on the slower speeds. Is there a fuse for high speed? What would cause this? How can I fix it?

 

Blower motor resistor, it normally takes out more than 1 speed though. What happends when you turn it to high? The blower motor resistor is located under the hood, beside the ac relays in the duct box. Its got a plug and 3 bolts. Its to the right of the drier.