Blower motor switch?

[BoondocK5]

I tried finding the search option here on the new page, to no avail, hopefully I'm just being blind.
Anyway, my 73 shortbox only has one speed for the heater/defrost blower motor. Off, and High, no in between,
Is that the switch itself, or do I have more of those.little.gremlins in the wiring?
I will attempt to find my Chilton book for this year of truck, it's buried, I'm sure.
What say the brotherhood?

 

[diesel4me]

There is a resistor on the heater core "box" under the hood that gives the 3 speeds,it is likely the coil for "medium" speed has failed...could be the switch too,but the resistors usually fail first..you'll see three wires with a plug that clips onto the resistor,a couple screws holds it into the blower housing..