2007 Pont Solstice - A/C & Temp Problem

[sbebenelli]

I have a 2007 Pontiac Solstice with 18,000 miles. Customer complaint is AC will stop blowing cold and in the instrument cluster where the odometer is you can page through different options and one of them is engine temperature, that will read --- instead of the engine temperature. They did not associate these problems as being together.

I pulled the car in and it has a code of P0128 coolant thermostat in the engine and under transmission it has a code of P0115 coolant temp circuit problem using a Snap On MODIS. Shortly after running car the AC kicked off, so I looked and the temp reading was showing ---. I looked at the temp reading on the MODIS and it read the correct temp. Wasn't long and the AC kicked on and at the same time the temp in the cluster started working. It appears as these two problems are related. The car has been here three days and I haven't been able to get it to act up since.

What confuses me on this is the MODIS was still reading a temp so I feel the coolant sensor must be OK and even the circuit. Has anyone seen something like this before? I've checked iATN & Identifix. This being a Solstice not much shows up.

[steven kiser]

it sounds like a default to prevent an overheating issue. when the pcm detects an overheat it will shut down the a/c. you may need a tech 2 to deal with this one. it may be a reprogram issue. the code for the t/stat will trigger if their is a circuit issue. it's natural for the p.c.m. to throw both. it's like a loose shoe because of a broken lace. briefly, i would look at the schematics and see if there is a fail safe after the pcm but before the gauge. i don't have accessibility to my diagnostics right now but it would come as no surprise if the pcm read the switch, fed the information through a gauge module and that's where the issue lies. it may be a cluster issue. i'm seeing the pcm's distributing their duties to other modules. i like the good old days where one module controlled all. no muss or fuss. just booted up my diagnostic program and am seeing a tsb for instrument panel wiring repair. may be a wild goose chase but anytime i see a bulletin about harness repair or replacement that's where i go first. a loss of signal and a bulletin on wiring kind of goes hand in hand.