Thread: 2007 Grand Prix heater not blowing hot air

take both heater hoses off the engine run a garden hose through one hose to flush it out. fill both hoses as much as you can and put them back on. you'll also want to bleed any air out of the engine via the bleeder screw on the t stat housing.

let the car warm up, ( this can take 15 to 20 minutes sometimes) cap open on the rad till the fans come on, then open the screw a few turns, till a stream of coolant comes out, top off the rad, and cap it.

chances are you have air in the core.