'07 Grand Prix heat problem

[GenesisGuy70]

2007 Grand POS (Prix)

Car hardly puts out heat. More heat comes through under acceleration. Temp gauge goes up and down.

Heat core clogged?
Bad thermostat?
....?

And yes, it is full on coolant. Obviously.

 

[Chris Meutsch]

The gauge moving around makes me think the system is clogged up.

 

[mclasser]

Could be air in the cooling system. Try burping the radiator and also checking for leaks somewhere.

 

[ls1mike]

How many miles? Could be a the water pump.

 

[55Test]

I wonder if the heater core is plugged. They can be done from under the dash. My brother did one in about an hour on mis old 2005 GP. Also check the coolant elbow

 

[dishdude]

Did you take the rad cap off to see if it was full or just peek in the overflow?

 

[Kawiguy454]

screams thermostat bad to me. And a cheap one to try before going further. Temp gauge shouldn't really move around much. Of you DIY make sure you bleed any air if you have bleeders in there. Last Chevy lumina I had had them.