Thread: 2007 GP GXP AC Keeps getting disabled. Temp gauge erratic but not showing Hot

I am sure hoping someone can keep me from going to the dealership with this problem. My 2007 Grand Prix GXP has a really strange problem. The car has just over 100,000 miles on it. When you get in the car and first drive it you can go about 10 miles and suddenly the "AC HAS BEEN DISABLED" warning comes on the screen which is supposed to mean the engine is running hot. Of course then my fans are running at high speed and I have no AC. The whole time I'm looking at my temp gauge it is not showing the engine is running hot. The gauge by no means appears accurate though as it reads rather low at times then higher above the halfway mark at other times. The fact that my AC gets disabled and the gauge only reads at about 1/4 of the way up makes no sense. I changed the temp. sensor with a brand new Delco sensor from the dealership just to make sure it wasn't defective. Now here's the even stranger part. When I disconnect the battery after getting that AC warning to reset the computer, I can drive the car for many many miles and it never trips that that warning again and the gauge seems fairly accurate. The next day the very same thing happens. Get in the car first thing, AC disable warning comes on about 10 miles into driving, reset computer by disconnecting battery, everything goes back to normal til I'm done driving the car. I have never seen such a strange problem like this and wondered if anyone has any suggestions. I was going to change the thermostat but it is very difficult to get to and just doesn't seem like the problem if the gauge isn't showing the engine hot in the first place. Any help with this problem would sure be appreciated

If you have the Torque app you can check the temp against that, but I would not rule out anything to do with the battery itself or the charging system as this could be an electrical gremlin. You are correct, the thermostat is a real b!@#$ to replace without removing the front exhaust manifold as GM suggests but at 100k it is time for a new one as well as a coolant flush.

I have a 2008 Grand Prix GXP, and the one time I had that message was because the AC Compressor was making noise. I don't think the two problems would be associated.