blowing cold while idling

My wifes 2006 impala lt blows cold air when the heat is on while idling. Once the car going, it will blow hot air again. Any ideas???

Low coolant, bad t'stat, air in cooling system are the usual issues.

low coolant would be my guess. mine started slowly being low on coolant the out of nowhere the radiator went out so hope you have better luck that i did

Low coolant yes, but wont notice if you remove the cap.
There are air pockets in system. Air in the heater core means no heat into the car.
If the water pump is not leaking, the most common cause is the rear head gasket. They leak externally and internally. Can see the external by looking down where the trans and rear cylinder head are. From under the hood on the drivers side. You will see wetness running down. Very common cause.

put some coolant in there and that seems to have helped. thanks.

the heat is how i know when my antifreeze is running low in my 04. I will fill it to the top while running, and let it idle.. the air will find it's way out.. keep filling it.

Where are you filling it? I would assume the overflow?

How long are you letting it idle?

Where are you filling it? I would assume the overflow?

How long are you letting it idle?

with the engine cold I fill it from the cap on top of the radiator untill it drips out a little, then i pull on the throttle cable a little to get it pumping. it will bubble and then settle again and i will top it off again. after it's settled all that it will, i will cap it and top off the overflow. you want to be done with it before the engine gets warm or you will not get it full.
I find that I have to do this about twice a year, half a jug of 50/50 at a time.