1999 Intrepid with 240k miles blows hot air only at high RPM
I've got a 1999 Intrepid with 2.7L and 240,000+ miles. This winter it started blowing hot air only at about 1500 RPM or higher. At idle, it blows cold air.
I'm assuming that perhaps the heater core might be slightly plugged, but it's just a guess. Based on the info on alldatadiy.com, it looks like replacing the heater core on this car is a real chore and a half.
Anyone have any ideas on whether my theory is accurate, and if so, best way to proceed short of replacing the heater core?