I have no heat. The blend door works, and the blower works. What to check next?

Make sure coolant is full.... Possible restricted heater core.. Feel heater hoses with engine at operating temperature, 'both' should be hot! Core can be flushed...

possible restricted heater core, no flow = no heat

same problem with mine for the last 3 years - ford lead tech said duct damper door breaks - $450 for part ,8 hours labor by Lincoln labor book. found a customer of mine that experienced same problem , she traded in the car . I'm attempting to locate this damper , just ordered factory service manuals ( $ 157 ) to assist in locating , then I will evaluate. Check back in a week or 2.....