You'll have to check voltage at the board from g and c. You should have twenty four volts. If not that is your issue. If you have 24 volts there then it is most likely your board but I would still check the voltage to the motor at that point. If there is no voltage I would replace the board. Some boards particularly on older units do not have a y on the board. If that is the case you would measure from the c on the board to the y junction that is in between the thermostat and the condenser. But since the condenser is coming on we already know that it has 24 volts. Generally the thermostat controls the signal for the motor in cooling but when heating it could be from a sequencer if you have electric heat or a limit switch if you have gas. Newer boards it is usually controlled by the board after a series of operation. I can't read the sideways picture to read the diagram to explain your wiring. Otherwise I would