I have a 2000 Grand Prix with the same problem. I found this response on another website:
"The problem is the blower motor resistor. This is a very common problem. It is located under the passenger side of the dash in front of the blower motor. The replacement part should be an updated and improved design."
Now I just have to figure out how hard to get at this is gonna be.
Good Luck.
I had the exact problem w/ one of my own. It is the resistor board. It is common on GM vehicles newer. They redeigned this particular part due to failure history. It is simple to change;also. It is located on the righthand side of the vehicle inside the cabin. Look down in the corner near the firewall and you will see a cvr that needs to be removed. After removing that cvr you will see a harness with a plug on it. That's it. Remove the two screws and wala the resistor bank appears. Reverse these steps to complete. HAVE A GOOD TIME!!!
it is probley not the blower switch. if your fan runs on 3,4 and 5 it is your blower motor resister.
The fact that you are having blower motor AND headlight problems points to ignition switch failure. Power to both systems comes from the ignition switch and this is a common Grand Prix problem. Here's the fix: http://www.clubgp.com/newforum/tm.asp?m=20670
Bad fan switch Bad fuse Bad resistor pack on blower motor Bad blower motor
blower motor bad or no power to it chech fuses blower switch blower motor
Blown fuse, bad blower motor switch, blower motor itself, or a defective blower motor resistor pack.
it is on the firewall and difficult but not impossible to get to and replace.
If a 2000 Grand Am sometimes has the heater blower working and sometimes it won't, the problem could be with the heater relay switch. The heater relay switch lets the heater blower know when to come on and when to go off. In most vehicles this switch is behind the glove compartment. This part sometimes gets corroded from condensation in this area.
Typically a relay or resistor. But could be a blower switch or blower motor problem.
Bad Blower motor fuse Bad blower motor resistor Bad blower motor Bad switch Evaporator plugged- not allowing air flow
blower motor resister is bad
Blower switch and connection had a melt down.
Bad blower motor fuse? Bad blower motor resistor pack? Bad blower motor - checck to see if it is getting power--if so bad motor Bad switch?