Carbon smell when Air blower is turned ON

[sgupta]

Hi,

I get smell of carbon in my 97 Sentra through the vents if the blower is kept ON and the car is left ON in neutral for 5-10 min. The AC works fine and if I turn it ON I dont get any smell though.

Any suggestions which filters I need to change or is it some other problem? I already replaced the air filter but I don't know if any cabin filters need to be change and where it is.

Thanks.