Furnace Blower stops working after 15 minutes

Question

We have a WeatherKing GU-80G-D3 unit. When the unit turns on, everything works fine for about 15 minutes and then the airflow stops throughout the house. This is true for A/C and for heating. Started doing this in September with A/C and we haven't needed heat until recently.When the unit does start up, I can hear a humming that lasts a long time before the air starts blowing. It sounds like the blower fan is having a hard time getting started. I am assuming our blower fan is having a problem but wondering if replacement is necessary or taking the blower out and cleaning it would solve.Any help would be appreciated.