Grand Prix's seem prone to various electricla problems. Mine has one too, but different than yours. I've heard the AC problem before though, and it seems to be solved usually by replacing the ignition cylinder. I know it sounds weird, but from what I've read, it generally works.
Good Luck --
jwardl
Roman B. wrote:
Hello,
>
> i have a strange electrical problem with my 97 grand prix.
> The air conditioner doesn't work at all, unless the fan speed is
> set to 5 ( the shop u took the car tried replacing some relay that > controls
> A/C speed - that didn't help ) If the fan speed is not set to 5, trip
> computer does not work also. After something broke there, gas mileage > fell
> down to 8mi/gallon. I took the car to the shop, they say there's a
> short circuit somwhere, which causes all of this, but they do not know
> where exactly to look. There's some strange device they suspect, it's
> located on the fron right side under the front panel, you can see it
> if you lift floor mat.
> The device has GM printed on it, but nobody can identify it, and it's > too light
> for an amplifier.
>
> I would appreciate any help diagnosing this problem/identifing unkown > device.
>
> Thanks, Roman