Pontiac Repair: No heat, dash vents, sound changes

Question
When I turn on my heat, only cold air comes out. I'm wondering if it sounds to you like the heater core? Do you have any idea how much that would cost to fix on a 2008 grand prix? Or how hard it would be to fix on our own? Thanks.

Answer
Hi Patricia:

it can be a few things. turn the blower motor on hi and then swicth the temp control from cold to hot and see if you notice a change in the air flow or the sound changes for the blower motor. Put the mode on dash vents and you should feel the air flow change if the temp door is working in the heater box. if you don't feel any change or don't hear the blower motor change chances are you have a bad temp door actuator in the heater box. if it changes then the next thing to check is to make sure the coolant is full in the radiator and in the overflow bottle. check it cold they should both be full. If either is low you have a leak more so if the radiator is low you have a leak if just in the over flow it's low it can be from evaporation over time. once they are full start the car up and let it run for 10 to 15 minutes touch the hetare hoses going into the car by the fire wall they should feel about the same If they don't you have a plugged heater core. Hope that helps. Good luck :-)