why does my car keep running hot? i have a 2006 pontiac grand prix?

[Just a girl]

my car keeps overheating and then it will read...please turn ac off to protect engine it was running hot three weeks ago and I added coolant now its doing the same thing...there are no leaks or anything...

 

[jiles357]

It could possibly be the thermostat is or has gone bad. That sounds typical if the A/C is on when this happens. The other reason is because the water pump has gone bad which. Neither on of these is a costly repair. A thermostat is only about 3 or 4 bucks and a water pump might be $100 installed. Hope this helps.