1999 Dodge Intrepid - No heat

1999 dodge intrepid blows cold air no heat

Is the temperature gauge in the normal range? Is the radiator and reservoir full of coolant? Does it blow hot air in the defrost setting?
Is so then you may have air in your heater core or a blockage preventing coolant circulating through the heater. You may have a heater blend door malfunction, not uncommon in older vehicles.