Truck Heater Not Blowing Hot Air?

My truck heater blows hard, but does not get hot. If I turn the mix down it gets cool, but if I turn the mix up to total hot it gets lukewarm. There is a new thermostat, new hoses, and new fluid. It just don't get good and hot. The scan shows 180' hoses in and out of the heater core are hot going in an cool coming out. Could it be blocked in the cold hot mix? Can someone help?

By Keith