I have a problem with my 02 Grand Prix SE: the interior fan control only works on setting 5. Settings 1-4 are just like as if the fan was on OFF.I tried a new switch and that isn't the problem. Could it be a ground problem? I often do get a bit of a shock (like a static electric shock) from the door when i get out of the car.

It's the blower motor resistor. It under the dash, behind the blower motor. $30 for the part.

Here's a how-to on it: Blower Motor Resistor

Damn someone finally went out and put that up. I gave someone a pic two months ago, but no Outline like that!

Great write up! I need to do that soon, my number one setting as never worked for me

This same things is happening to me, how do you know if it's the resistor versus the switch though? Thanks!