I didn't believe my wife, but the heater starts blowing cool air after a period of time. I drove the van twice this weekend and both times the initial heat temperature did seem a bit cooler, but not problematic. After driving a for a while (20 plus minutes) the heat turned cool and remained that way for the final 10 minutes. The first time we where on the highway, but the second was in town. Engine temperature ranges for 178 to 230 and problem does appear to happen once temperature is goes above 220. Coolant level is between min and max. Problem may occur after switching to defrost though switching to defrost doesn't make it happen every time.