Pontiac Repair: blower motor, blower motor resistor, grand prix gtp

Question
i have a 2005 pontiac grand prix gtp with a 3.8 supercharger. the other dayi had a whistling coming from the dash. assuming idts the blower motor. now when i turn off my car the inside vents are still blowing air with car off. cant change the fan speed or even turn it off. all the other knobs work for hvac except fan speed. what to do?

Answer
Hi
I would HIGHLY suspect the blower motor resistor. It is located under the dash, passenger side close to blower motor. On your vehicle it is a rather tedious job, as the resistor is held in by 3 screws and one of them is against the firewall.
Do not know if your going to DIY, but if so, take your time. It is an easy job, just difficult to get that one screw.
I do hope this helps.
Good Luck
God Bless
Pawl