I have a 2000 Yukon and the problem I am having is no heat coming out of the front vents. The rear blows hot like normal but the front is barely luke warm. I checked the blend door actuator right above the transmission hump and it works fine. I guess now I will try flushing the heater core but needed some advice before trying. How hard is it to disconnect the heater hoses from the heater core? Which side is the inlet and which is the outlet? What is the best thing to use for flushing it? Any help on this will be greatly appreciated!