I recently replaced my radiator on my '01 Millenia. I bought this car in the summer (Texas) and when it began to overheat I cranked the heater until I could pull over and check it out. It seemed to me that it was working, but it was summer in Texas so it's kind of hard to tell. At any rate, I replaced the radiator, but now my heater is not working. I am wondering if I could have created a vapor lock or something that would prevent coolant from getting through the heater core. I have tried all the other suggestions for getting the heat going except for flushing the heater core and or replacing it. It seems to me that there is a little warm air and a slight heater smell when I first turn on the heat, but it turns to cool air very quickly. Any suggestions are appreciated. My seat heaters are also out so I am freezing!

 

I got some warm air this week, not hot but warm. When I turn on AC to defog the windows however it blew cold immediately. I was encouraged to have even a little warm air so I flushed the heater core with water this morning hoping theree was a partial blockage. I get only cold air now on every setting. The top heater hose is hot but the lower one is cold. Does this mean I have to replace the heater core? If so, what should I expect to pay for the part?