2002 No heat while idling

The old 2002 is misbehaving. Lots of heat while driving but come to a stop and she immediately starts blowing cold air. Heat kicks in just above 1100 RPMs when parked. Anyone know exactly what the problem is??????

Water pump possibly.

^^yup yup

Thanks. Just ran out and found the coolant low. Apparently a low coolant condition throws an engine light and kills the heat at low rpm.

Coolant low= Coolant leak!
Check the sides of rad & all hoses for a leak!
& keep reservoir topped up using the right coolant, until you can find & repair the leak.
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Air in system from leak not good either.

Pay close attention to the LibertyTC patented "Hoat Coolant Sticker"

Yeah low coolant could definitely affect your heat.. but it's funna affect plenty more as well..
I've run into a decent amount of coolant leaks on my libby and never had it throw a code because of it..

If you can't find the source of the leak, sounds like a pressure test is in order.. but I'd pay close attention to your water pump mounting gasket and the weep hole on it as well..

Just wondering why some of you automatically assume that the water pump is at fault when someone posts "no heat" type of post?

20+ years turning wrenches professionally on all types of vehicles and have yet to see a WP cause no heat at idle without(key word here is "without") the engine in a overheating condition also(impeller gone,broken,or wrong pump installed).Now a leaking WP can cause a low coolant condition this but that is a leak and the low coolant is the actual cause of the no heat.

The most recent one was the guy complaining about the design of his heater core..
Heat dropped at idle. "Without" overheating. And hasn't posted since water pump replacement.......gunna go with there's your example..
He also had "no" coolant loss.
I've had the same condition with mine. No coolant loss. Freezing temps at stops. Never overheated. Water pump fixed it.
Pretty sure CzarKJ just had a similar condition that was fixed by a water pump.
That's three very recent examples.. so sorry you haven't experienced this in 20+ years.
perhaps to you these don't seem relevant to the current post, but it's not like we said yes, definitely your water pump and couldn't be anything else.
But if you look, he didn't mention coolant loss in the first post. Nor did he mention overheating..

I have no heat also at idle in a 2010 jeep liberty. I changed thermostat before and flushed rad and heater core. There's only heat while driving. Coolants topped up.