So my 2011 mustang gt will occasionally overheat on a hot day at idle I already changed the thermostat and it still overheats anyone know why??

 

Is the fan coming on?

 

Yeah I think so I'm not sure if it's on when it starts overheating when ever it over heats I try to drive it as fast as possible so it can cool down I never had a chance to get out and look at it

 

yep most likely the fan is not coming on, or not coming on soon enough

there are two fan speed settings, hi and low, which kick on at a defined temperature which can be adjusted in the tune -- so if you installed a new tune shortly before this started happening, that could be the cause (but most tunes turn them on sooner rather than later)

otherwise it is probably the relay, if I remember correctly from other threads I have seen on here -- you should be able to find them, with the details, using "search" feature

one quick and easy way to test: turn on the A/C; the fan should come on when the A/C is on . . . if you let it idle with the hood open it could take a while but that is the best test

 

Thank you very much I will try that and hope that's the problem