Disclaimer, I am not an electrician or in any way qualified to give electric advice. Following my instructions may result in a fantastically painful death and/or total loss of property and innocence, but probably not.
It's man's nature that if you have a motor capable of three speeds you will want to use all of them. Such was the case when I was looking for a motor for a small shop project. My choices were between a 1/4 HP single speed motor or a 1/4 HP three speed HVAC fan motor. The fan motor was designed so that you pick one speed, wire it, and that would be your speed forever. But does it have to be that way?
So you want to know how to wire a 3 speed HVAC direct drive AC motor? Here’s how I did it.
1 each – SPST (on/off) Gardner Bender toggle switch
2 each – SPDT (on/off/on) Gardner Bender toggle switch
wire, motor, and appropriate electrical housing w/ cover
Turn off the first switch before changing speeds with the other switches. If you know of a more elegant way, feel free to post it in the comments below. If you believe my way will be my doom, well I'm here writing about aren't I?
Update: for clarity: Green = ground, white = common, black = high, blue = medium, red = low. If you have more colors I don't know what they do.