If footwell vent is hot with temp controls set to minimum (60F?) and AC off, then I think it's safe to say the drivers side heater valve is leaking or stuck open due to debris. This assumes your outdoor temps are above 60F, so IHKA isn't calling for heat, and there are no other problems. My understanding is the heater valves need 12v to stay closed, so an electrically disconnected valve will be wide open putting full hot water flow to the heater core.