Thanks for using Just Answer, the most common cause of the problem you are having is a defective Temperature blend door actuator. (Click Here for Instructions). Hope this helps you out.
Before replacing the Blend Door Actuator, make sure cooling system is full and there are no air pockets trapped in the system, also while the engine is running make sure both heater hoses are very hot, if one is cooler than the other suspect a plugged or restricted heater core.
If the hoses are only getting warm, (must be very hot) suspect a defective thermostat, as long as there is no air in the cooling system.
A/C Electric Blend Door Actuator
The A/C electric blend door actuator is located on the plenum assembly.
If all those things are working properly, then you should have heat in the vehicle, unless the heater core itself is plugged and not generating the proper heat.
INSUFFICIENT, ERRATIC OR NO HEAT
Thank you for asking your question on JustAnswer.
The other Experts and I are working on your answer. By the way, it would help us to know:-Do you have the manual or automatic control?Thank you again for trusting us with your problem. Please reply as soon as possible so that we can finish answering your question.
Ford did have problems with the EATC (Electronic Automatic Climate Control), however I would first suggest performing the following tests before replacing.
Electronic Automatic Temperature Control Module Self-Test
Hi work 6930,
The blend door actuator is located on the plenum assembly. Under the dash, towards the center.(Click Here for Instructions).
CLICK HERE FOR COMPONENT LOCATIONS
Awesome good job, it just sounded like the coolant was low
CLICK HERE FOR INSTRUCTIONS