In A/C mode, blower motor will not come on. I replaced motor and capacitor but it still does not come on. Will not run with thermostat in RUN mode either.

The A/C fan blower motor relay is probably defective. On some units it is located on the control circuit board located in the furnace. It also usually means you have to replace a expensive control board. Before replacing the control board/relay I would perform the standard tests by electric meter or jumpering out the relay on a temporary basis. If the circuits would have been tested first you might have saved the expense of the new motor.