3-speed blower wiring

[Jake Helmboldt]

I finally got around to building my shop air cleaner w/ a three speed furnace blower (squirel cage). How do I wire it for all three speeds? It has a red, white, and black wire coming off of the motor, and I've managed to run it at its high speed by wiring a plug onto it, so I know the motor works. But I have no idea how to wire it for the speeds.

Thanks, Jake

[Bill Turpin]

White is neutral, black is USUALLY high, red and blue can be either med or slow. You can't get three speeds with only three wires. Connect power to white and only ONE of the others. Check for which speed for each combination.

Bill in WNC mountains

[J Simpson]

Generally, the black wire is high speed, blue is medium, and red is low speed. At least that was the way that the blower I use was. You only want power to one of the three speeds at at time.

Edit: Bill is a much faster typer than me.