92 F150 Supercab 5.0 Auto Tran.

The temperature Control **** became difficult to turn toward hot.
No warm air comes out under any setting (vent,floor,def,etc.).
Blower works, swith to adjust vent, floor, AC, etc. works.
Both heater hoses are hot, Radiator is full.
All fuses are good.
I took out the Glove box and verified that the Temp Control ****
was actually moving something. It's attached to a cable that moves a white plastic lever, back up in the dash. From what
i can gather from the web, i might have a "blend door" problem.
How can I confirm that? If it is, i hear it's a $700 job to replace.

I'm gonna take it to my mechanic, but thought I'd try everything I could first.
THanks....

 

I just competed a repair of what I thought was a blend door problem. The only thing is I don't know if your 92 uses the same engineering as my 98. I replaced the blend door actuator (68.00) and one of the vacuum control motors that opens and closes the floor/panel door. There was another motor that sat above the floor/panel motor that regulated the defrost/panel blends. As I was looking around this motor I found the actuating arm had actually popped off the door mechanism and was easily reattached with a lock ring. It solved the problem, so you may want to check this out before taking it to a shop.