97 ford f150. ..
Here is what I know ...
*Coolant level is good
*Thermostat is good
*Heater Core is good. . Both hoses heat..no leaking. ..
*Upper Hose gets hot
*Blend Door works.. I cut into box and seen it open and close...
*No air in system
*AC WORKS

Could it be a fresh air door?? A vacuum line??? My EGR vacuum isn't working properly is there a connection?

 

If both heater hoses are hot ...then you have hot coolant running through the core.. something preventing the heat from the core.. Blend door would do this but you say it's good...with the blower on what comes out ? cold...warm ?

 

The air was cold... core felt hot

 

Blend door not opening to let air flow through heater core.

Its the only thing.

 

Well I see it opening and closing when I turn it from hot to cold

 

The only other thing is the coolant not flowing through your heater core to warm the air going through it.

 

How do you see the blend door opening and closing?

 

Perhaps he cut a hole, just as I have done.

Maybe you're heater core is clogged like 75% of the way. Maybe you should do as I am planning and taking temp readings of the entire core with an infrared thermometer?

 

if both hoses are hot it has to be flowing through the core

 

The op stated he thought the blend door was functioning properly. I was just asking if he had seen the blend door functioning properly.