Yes that is what it seems to do. It will start out reading the temp get close say 160s/170s then it will blank out. the next time I drive around it will start out blanked and then it will randomly start working after awhile.

The wiring all looks factory still I have unplugged and replugged in the wires all feels secure.
I will get a Delco on order and see if that does the trick.
If I decide to do a drain and fill how many gallons go into the HHR?

 

Also when the mechanic friend had the scan tool he said it looked like everything was talking to the computer, so it doesn't seem like a short to me, but then again the computer is what is shutting the AC off.

Thanks again for your help guys.

 

Depends on the year and engine you have. You didn't give that info. The capacities are listed in your owners manual. If you don't have a manual, they are available "free" for download on this site.

The 2010 manual shows these:
Cooling System
2.0L Engine 9.2qt 8.7L
2.2L Engine 7.4qt 7.0L
2.4L Engine with Automatic Transmission 8.5qt 8.0L
2.4L Engine with Manual Transmission 8.7qt 8.2L

If you do a drain and replace of the coolant, make sure you are aware how to burp the system when filling. It avoids leaving trapped air pockets that will give false coolant temp readings.
There are several threads that discuss this. Try the Search function. I don't have time to find those threads right now.

 

There is a link in my sig for an online Owner Manual. Fluid capacities and lots of other info is in it.

 

K I'm out!!

 

Wasn't that explained earlier?
I won't go into my opinions about ASE certification.

I'm out, too.

 

I have an OEM T-Stat on the way will change it out this weekend.
Thanks for the help guys.