No definitely not reversing while running. the existing control box already handles the stop start and timing. I just need it to turn a different dirrection each time it is started. so I'm trying to add after the existing control box.
I'm thinking of disconnecting the condo at the motor, add a latch relay and DPDT relay after the existing control box, cable in the condo at the DPDT and feed a 3 wire cable to the motor.
Good point, KISS.
Also, any control circuit will have to ensure that the direction of rotation (assuming vacuum is possible in both directions) is set before power is applied to the motor. So IMO two relays will be needed.
The YN series is reversible, but no wiring diagrams on the site that I can find. Though it might be a synchronous motor, but they already have a category for that.
I'd check for a motor nameplate with reversing instructions or look for wires labeled with things like T1 T2 etc. Sometimes all of the wires are black with white lettering on the wires themselves.