Need help not getting any heat inside my vehicle.

What is your question?

I am having a heating problem the fan will blow air out but its cool air only. Heat temp is set to maximum. I Changed the thermostat but it still blows cool air. Thought it could be a heater core but the windows inside don't fog up the windows. Do you have any suggestions?

What makes this problem better or worse?

small amount of warm comes out after running for a while

How long has your 1990 Chrysler LeBaron had this problem?

3 weeks