My problem is that prob 90% of the time it blows lukewarm air and 10% of the time it has the normal hot air, blowers are working fine, thought if it was heater core bad it would blow cool/lukewarm all the time? Also the temp control is working fine so im guessing the blend doors are working also. 2003 Dodge Ram 1500

 

Sounds like the blend door. The temp control doesn't control air direction. The door is probably allowing too much outside air in.