Deal!

 

In my case, an ink pen had fallen in through the defroster grill and was jamming the blend door and preventing it from completely closing. It would still open fully and close to about 75%.

 

how the hell did you get a pen down there?

 

It was there when I bought it used. Kids maybe?

 

try this simple test before you buy anything. the heater core is very east to get to in most ford trucks it is behind glove box remove small panel and feel heater core when engine is warm if it is cool then check your flow valve operation maybe vac. line is off. I had this problem once it was a crack in the vac. line fix with black tape cost was about a penny good luck

 

A vac line controls the flow valve?

 

heat and cool it is all vac. operation, start with easy first you can check water flow at firewall by just feeling the hose. are you getting any air from the vents? I have seen a/c air coils clogged on some trucks before this will all but stop the heat.

 

Yep the fan puts out a good amount of air. It's just not nearly hot enough.