98 Durango with 5.9L and 116,000 miles. Barely any heat and like another post you only get heat when the RPM's are at 2800. It is not the blendor because at 2800 if you move the blendor from cold to hot it gets hot and cold. I've recently had the evaporator replaced and the heatercore with it but this symptom started last winter and I assumed the heater core was the culprit when my mechanic showed it to me. I've also had the engine/ coolant flushed, replaced thermostat, fan clutch, upper and lower hoses (raidator). HELP I'm freezing! Temp gauge barely moves past halfway between the 130 -210 point which means I have a temp of 170.