1998 Chrysler Concorde what might be the problem?

Tammy:
First make sure the coolant level in the engine is full. If it's low, it could cause the problem you described. As far as the t-stat, if you follow the upper rad hose to the engine, it will end at the t-stat housing. Under the housing is the t-stat. Before you replace it, check the temp the engine is running. Does the engine warm up to a normal operating temp or is it running cool?

Let me know what you find, and we'll figure it out. Also, I believe your interior temp is determined by a blender door. It takes outside air from the cowl through a plennium and based on how far open the door is open decides how much air passes over the heater core. If the door is damaged, it may be opening and closing causing you to feel hot and cold air.

Joe