Camtech is correct.
Both the inlet and the outlet hoses should be hot, all of the time, with a fully warmed up engine.
Hot coolant is always circulating thru the heater core.
When you change position of the heat / cold mode switch, the blend door will allow air to either flow over the heater core or air will bypass the heater core and flow over the a/c condensor core, if your car is eqquiped with a/c.
Some cars that are not equipped will allow the air ( outside or recirculated) to bypass the heater core, when the blend door has changed position.
If both hoses are hot, then the problem will be with the blend door, blend door acutator motor, heater mode control panel, vacuum lines, wires, connectors.