2000 jeep cherokee no heat at idle (Page 2/2) Formula88 MAR 22, 01:51 PM If it's not an air pocket, it sounds like a restriction of some kind. You say the heater core flows freely, so I'd look at any actuators or valves that control the water flow. The symptom sounds very much like a clogged heater core. fierofan25 APR 13, 12:02 AM Installed new heater core and it still the same. I do not think it is an actuator because it does its it so quick. Im not to sure what else to try. Venomous APR 14, 02:56 PM How many miles? 4.0L? Does your water temp rise when at idle too? Ive replaced a few 4.0 (assuming thats what you have) water pumps because they get old and cant pump enough at idle to flow coolant through the system. Just something to look for.