heater

Aside from this site being much too cumbersome (it is not overtly clear how to pose a question) I pose, to Chrysler engineers or whomever has the answer, why does my 2000 Sebring car heater initially blow hot air within 5 minutes of starting the engine, then cools down and doesn't again blow hot air until about 15 minutes of running the engine? My mechanic topped off the coolant; still have the problem!

air bubble trapped in heater core.If u have a 2.7l engine its common for some one that does not not know to fill the coolant system up with the right tool.
IS your heater core,water pump  or Water outlet housing leaking. Air can be trapped if there is a leak in any of thoes places.

This problem began last winter, and there was never any overheat of the engine thru this past summer, so I doubt a low coolant problem or a leak. Also, why would the engine jacket/heater coil system, as it first heats up, and after supplying hot air, then deliver cool air, and then return to a continual supply of hot air? I sense that perhaps there is a thermostat connection between the engine jacket and heater coil that is over reactive and is closing the initial hot water supply to the heater coil. But is there such a thermostat regulating delivery of water to the coil? I didn't think so; I thought the engine jacket/heater coil system was one continuous open system. The VIN is 3C3EL55H9YYT313?82, in case this tells you the engine size, a V-6. You seem to know your stuff. Thanks for the input. Any more ideas? I guess its time to look under the car for a leak. What's this about a tool to insert coolant?