I replaced heater core and flushed system and still have no heat. Hoses going to heater core are not hot
what was the reason for replacing the heater core in the first place? were you having heating issues? did you check the thermostat?
Having any radiator or cooling problems? If your coolant is low it will develop a vacuum in the coolant lines and it won't warm the heater core. Happened to me on one of my old Rangers. Water pump was leaking, I ran it low in fluid, no heat. Filled up the radiator and reservoir and the heat was back. Changed water pump and didn't have any other issues. Sent from my iPhone using Tapatalk
Check the vacuum line that goes to the heater core control valve on the heater core water lines. Make sure that didn't get disconnected when the heater core was installed.