2000 Chrysler Grand Voyager SE 6 Cyl 3.0L
Heater only produces heat when over 30mph, idle or stopping makes the heater blow cold air.
120000 miles on van, heater control was replaced used 12 days ago. Thermostat was replaced last year when engine was running close to overheating. The engine runs at normal temperature when warmed up does not overheat. There is a coolant leak which I top off every month. After warming up the heater only blows cold air until the van first accelerates to 30mph roughly. At which time the heater blows warm air. The faster you go the warmer the air. If you were to stop at a light or reduce speed under 30. the heat goes cold.
First, repair the leaks, then the heat will be back to normal.