where is the heater core on my 2006 Montana? I'm sure it is under the dash. what kind of job will it be? good heat until idling. same MO as last time the dealer replaced. thanks

doesnt sound right, did they flush the coolant? change the thermostat?

^^ what he said.

4 years and 200,000 miles ago it did the same thing: no heat when slowed down to an idle. my wife took it to the dealer and they said it was the core. cant find the bill or do I remember the details. this summer I replaced the original radiator and water pump but not the thermostat. If you think that could be the answer will try that. much easier than the core. never liked taking anything to the dealer but if it'* not perfect she can yell at them and not me!!!lol thanks again.

i would start there

If you don't have heat at idle, I am thinking a coolant leak is causing an air pocket....also, I think on those vehicles, there was an auxilliary coolant pump located under the brace behind the driver'* side headlight assembly....

I have also see a failing Lower Intake Manifold gasket result in poor heat delivery. Might be worth doing a coolant system pressure test.

It still has the original thermostat at 298,000 miles. that I WILL change. I have a history with air pockets on a 4.3 and a 3800 after coolant changes. I'm still leaning that way. It has the same symptoms that required the heater core to be replaced a few years and miles ago. no leaks, its not low on fluid. will have to wait until sunday now. Have good starting points. thanks again.

the 3800 has a bleeder screw you open and fill it slow, then close it when fluid comes out. if the 4.3 doesnt, run it with the rad slightly elevated and the cap off for a few minutes