I have a carrier furnace that has a low speed fan blower motor that will not shut off no matter how long I leave it running. I checked that removal of the G wire at the control board does not change anything. This should rule out the thermostat being an issue. I checked the furnace limit switch and it seems fine with good continuity at the two switch parts (the button part and the actual part that sticks into the hot zone). The heater works fine and will shut itself off when it reaches temp but this only changes the high speed fan. I checked continuity over the fusible link off of the limit switch and it has good continuity. Anyway since the heater works I read that it’s not a problem with the furnace high limit switch. I pulled the low speed fan wire off the control board and that successfully shuts off the low speed fan but then I hear a small humming sound from what might be the HFR or heating fan relay. So is the remaining issue pretty much just the control board or am I missing something I can check?