It is important to check the coolant level under the pressure cap, as well as the tank.

Normal running temp should be around 190F, so you are a little high.

Don't run the A/C until it gets fixed! 260F WILL damage the engine in short order. You need new Dex-Cool and coolant flush at the least after an overheat incident. Coolant changes character after it overheats and can plug things up.

 

Any MIL light codes? Like P0128?

 

I don't think a stuck T-stat would cause this. Maybe particulates got in the fluid somehow and clogged up or something. I realize it's pressurized, but still.

 

x2 - or if an incompatible antifreeze as been used, resulting in lumpy coagulated antifreeze (that was a mess to clean out years ago)

 

Or for that matter.... water....

 

I suspect the AC condenser and or radiator have some external blockage. Not enough to cause a problem under normal conditions but the added heat load of the air conditioner puts it over the top. Sometimes a simple rinse with a garden hose will help. Mix up some dish washing soap to put on the condenser and radiator to help loosen anything that is stuck to them.

An internal flush of the cooling system won't hurt either but you need a product designed to do that. Dexcool needs to be replaced every few years. In my opinion, the sooner you get the Dexcool flushed out of a vehicle the better.

It would ge a good idea to hook up a set of gauges to the AC to make certain someone didn't overfill it causing higher pressures and higher heat.

 

The OP hasn't bothered to come back since the 1st day of his posted problem.

Oh well.......we'll probably never know the answer to the fix.

 

I'm having this exact same problem with my 2009 hhr !! I haven't tried running it without a/c yet!! Going to try that today!! The clanking noise is coming from from my a/c compressor but mine not constant, only does it like when like the compressor kicks on!! Also when mine is at idle the compressor kicks off and it blows hot inside the car. I said added in another post I've yet to hear my cooling fan kick on!! Could my a/c conditions be causing my engine to run so hot?? What should I do??

 

I will update after I try running it without the a/c on!! May be later this evening cause this georgia heat is pretty rough!! Lol

 

shaneslife - you already have posted on another thread- I'm closing this thread rather than having the same problem tracked in two separate areas which just leads to confusion when people try and follow the issues.

Your current posting is at - https://www.chevyhhr.net/forums/prob...g-53515/page9/