Hi I have a 1998 Pontiac Grand Prix and the heater blower motor does not work, if I turn the ignition on and the blower motor is in off position my headlights come on. when I turn the blower motor to the 1st setting the lights go off but the blower motor does not work. I checked the blower motor with a 12 volt battery and that works. i put a new resister in and it did not slove the problem

04-08 Pontiac Grand Prix - Blower Motor Resistor ... - YouTube

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04-08 Pontiac Grand Prix - Blower Motor Resistor ReplacementPart 1 ..... Loosen, but do not remove the two frontward screws, then remove the single rearward .... Pontiac Grand Prix StereoRemoval 2004-2008 - Duration: 4:27. by Factory Car Stereo ...Pontiac Grand Am ,HVAC, Heater Fan will not turn on.

04-08 Pontiac Grand Prix - Blower Motor Repair (Part 1 ...

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Your ignition switch is bogus. High speed runs directly off the speed control but the lower speeds go thru the ignition switch. Do not know why but that is the way it is!!!!!!!!
Replace the ignition switch and you will be back in business.

The blower should stay on for about 5minutes to cool the engine off. It isn't a problem unless it is running continuously after the engine is cooled.

Check for power at the HVAC CNTRL fuse with the blower set at any speed less than high speed. There should be power anytime the key is in the run position. If there is no power turn off the blower. If there is power with the blower off you need an ignition switch. The ignition switch is what supplies power to the lower speeds.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Wires need to be tested at certain points to find out whats going on. It could be as simple as a bad ground somewhere. This needs to be looked at by someone with experience so that more damage is not done. Hope this helps.

Replace the blower resistor that is mounted next to the blower motor on the passenger side of the vehicle.
This will restore correct blower operation and I suspect it is also back-feeding voltage resulting in your electrical issues.
Two screws hold the blower resistor into the heater case and it is very easy to replace.
Good luck

under the dash below the glove box
if the blower motor is inop then
1st check for power on the purple wire at the blower motor
if it has power then you need a blower motor
if it does not have power then replace the resister
located beside the blower motor5-7 wire connector
TRICK TO REMOVING THE RESISTER
you will see 2 goldish colored bolts they are 5.5mm remove them
now the TRICK
there is a 3rd bolt you can't see pull down then pull towards you
this will BREAK THE RESISTER OR SLIDE OFF THE BOLT
then when the resister is out LOOSEN THAT BOLT OFF
the resister is slotted slide the NEW RESISTER in the bolt you just loosened then tighten the other 2 leave the hiden bolt loose
hope this helps

heater blower motor bearings are going bad...replace blower motor...Lee

I'd say that your blower motor resistor has shorted internaly.