On 30/01/18 22:53, Dave, I can't do that wrote:
OK, thanks David, for six-bucks and change, I'll give it a try. What's the worst that could happen {VBG}

I'll signal back if the magic-smoke escaped or not later this week. Or maybe I will be buying that 1/2hp motor I pine for.

I looked up swamp cooler motors and Grainger listed a number some being
split phase where a winding is switched out when upto speed maybe like
yours as no cap info was given on the rating plate so not suitable for
speed control but they also listed PSC swamp cooler motors so maybe just
a matter of choosing the right motor to suit voltage control.