I have a 2002 5.4L F-150. I had no heat. Removed dash and installed new heater core and thermostat. Now I have no heat or air. What is the most likely cure?

 

You don't have any hot coolant circulating through the heater core.

 

When you re assembled it. Something has probably unplugged... is the fan still working but no air out of the vents??

 

I have great air flow. Just no control over it being hot or cold.

 

Did you plug the blend door actuator connector back in?

Have you verified that coolant is flowing through the core?

Have you verified that the refrigerant section of the air conditioner is operating when a mode that uses it is selected?

 

Sounds like blend door actuator and or blend door