I have a hummer h3 that’s been overheating for a while now. Mainly in the summer when the AC is turned on but even with it off on a hot day the gauge goes pass the middle. I’ve changed the thermostat & water pump. What else could it be? Mechanic can’t figure it out, any ideas are appreciated!

 

Check this, post #3 is your answer

https://www.hummerforums.com/forum/h...-parked-27380/

 

Passed the middle is NOT overheating....... When it is in the red, then that would be overheating. Your "mechanic" is burning your cabbage for nothing.

 

I just performed my annual temp gauge check, @ idle in my back yard, enclosed with 6ft wood fence:

Outside Temp: 93degrees
KOEO: coolant temp: 113degrees
Startup: coolant temp: 115degrees
1/4 gauge: coolant temp: 154degrees
Thermostat open: 194degrees (drop to 190degrees)
Center 1/2 gauge indicator: 195degrees
Idle for 1/2hr: 199degrees
AC on for 15minutes: 201degrees

Indicator still points @ halfway mark, just to the upper part( scanner ect is the bottom line @201degrees):