Pontiac Repair: heater issue, pontiac gran prix, coolant level

Question
My girl friend has 2004 pontiac Gran Prix, with a V6 engine and the heater doesn't work when driving but blows hot hair when idling.

Answer
Hi derek:

any serveice engine soon lamps on? let the car cool down and then check the coolant level in the radiator and overflow tank when it's cold fill the radaitor up and the overflow to the full cold line and start there. If when you take the radiator cap off the coolant looks all rusty it will need a coolant flush you may have debris blocking the heater core up. if the coolant is indeed low then likley places for a leak are the intake manifold gaskets upper and lower and maybe a water pump. that is where I would start looking. good luck :-)