Ambient Temperature Sensor

I just found this forum and I hope someone can help me out.

The A/C on my 99 Grand Prix works fine except when the ambient temperature gives me a false reading of 37 degrees or less. The other day the temperature outside was 92 degrees and the ambient temperature showed 32 degrees. The point of the reading being incorrect isn't the thing that bothers me but the problem with my car automatically shutting off the A/C compressor as soon as it drops below 38 degrees is really burning me up. I can't even override the A/C by pressing the A/C button on the Climate Control panel. The car seems to think I must be crazy for wanting the A/C on when it's freezing out (Open the window Stupid!!). Maybe it's possessed? As soon as the temperature goes back up to above 38 degrees, the compressor will kick right back in. I was having this problem last year as well but I wasn't driving my Grand Prix as much as I am this year.

I have a feeling it is either the sensor or the wiring going to the sensor but my big problem is that I have no idea where the sensor is located.

Any help or suggestion wil be greatly appreciated.

Welcome to AF.

Yeah, it sounds like a bad ambient temperature sensor. It is located at the front end of the car in front of the radiator on the support bar. You'll see the wiring harness and sensor.

Its only a $8-10 part at a dealer easy DIY job

Thanks guys. I picked up the part yesterday and it cost only $10.09 with tax. It took me longer to find exactly where it was than actually replacing the part. With the temperature outside today reaching 101 degrees, it looks like it is working and definitely worth the $10. The dealer wanted to charge in the neighborhood of $90 just to look at it when he was probably already saying to himself it was the sensor and I'm going to make a good commission on this job.
Thanks again. :thumbsup:

Thanks guys. I picked up the part yesterday and it cost only $10.09 with tax. It took me longer to find exactly where it was than actually replacing the part. With the temperature outside today reaching 101 degrees, it looks like it is working and definitely worth the $10. The dealer wanted to charge in the neighborhood of $90 just to look at it when he was probably already saying to himself it was the sensor and I'm going to make a good commission on this job.
Thanks again. :thumbsup:


I'm having the EXACT same problem you did. Can you (or anyone) describe just WHERE that puppy is?

Do you get at it from underneath, under the hood, or what? Is it next to something? Is it easier to see the electrical connection and trace the wire up?

When I replaced mine, it was easier to see and get at it from underneath. I believe on the '99 and up models, there is a plastic piece that has to be removed before you can see it from the top. Just lie down and stick your head under the front bumper, then look up in the space between the radiator and the bumper. You should see a funny-shaped plastic thing and a connector clipped onto something up in there.

Seems like the air dam would be in the way.

just reach through the grill inlet on the bottom passenger side