I recently replaced the blend door, thermostat, radiator, and heater core. Flushed that all out as well and I still get no real heat in my vehicle. Maybe its the climate control unit? I'm out of options and am about to sell it, but I don't want to because it only has 91k miles on it. Please help!

 

could be a air pocket. when the truck is warmed up both lines going to the heatercore should be hot. along with the upper and lower readiator hose. if all that is hot then yeah might be something with your blend door