Hello n thanks for any help you can give me. I can't get the heater to work. I've flushed the core checked the heater valve the plunger moves as it should. I have hot hoses going into core and out to pump. Truck stays at halfway mark when warmed up. Air works fine. Checked the fuses all ok. Does this sound like a faulty door issue? I can hear the doors move all the positions seem right (turn to defrost works, floor works, all positions are working). The book I purchased doesn't do a breakdown or detail of the heater box. Any help is greatly appreciated. If this is covered within another topic I apologize hard to get a good search from my phone... Tks, badcreek
Just adding a note found the
Problem the actuator door was stuck closed aka no heat. When I got it apart I found the small electric motor was burnt out. The good news I have my heat and air working fine again.

 

Not an uncommon problem with Ford Trucks, and some cars.

It is the Blend door, and electric door

Google: Ford Ranger Blend Door

The Blend Door is used to cover the heater core inside the dash.
It is operated by the TEMP **** or control for COLD and HOT

When in the cold position all air is diverted around heater core by blend door
In hot position all air is diverted thru the heater core by blend door
And it can be adjusted to send 1/2 the air thru core or 3/4 or 1/4 or.............its adjustable to control the heat in the cab

Yours is broken
The electric motor can break, or the tab on the door that fits into the motor can break.

Look at the videos to see which broke on yours


Glad you got it fixed