I have a white rogers 50a50-471 supplier only has a 3 speed motor to replace 4 speed motor in trane xe80. Can this work and how to wire to controller

This is the replacement for the W/R board you have

http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_pages/Cat_06_pg0066.pdf


These are the instructions for the new style board

http://www.white-rodgers.com/wrdhom/pdfs/instruction_sheets/0037-6265.pdf


Trouble shooting

http://www.white-rodgers.com/wrdhom/pdfs/06_Cat_pages/Cat_06_pg0259_264.pdf

On the W/R boards you have a selection for one speed for heat and one speed for cool. The rest of the terminals are maked park and you can just park the extra wires there since they have no effect on the operation of the furnace.

Usually cool is the highest speed available on the motor and heat is usually the second to the lowest speed on the motor. The motor will have a diagram on it or the blower door will have a diagram on it.