Blower motor inop @ hi speed setting

[69redrunner]

69 Roadrunner, blower motor runs well on low and medium settings but stops when high speed is selected.
Is there a hi speed relay somewhere?
If no relay, could the actual switch be the problem?

 

[Cranky]

The resistor is what gives the lower speeds and when the switch is on high, the motor gets full current. I would say the switch but it wouldn't hurt to check the resistor too.