Hey guys, stuck on this issue. my 2011 grand cherokee runs fine expect when I climb a hill. The temp rises all the way to max. If it is a long climb I will lose power. As soon as I crest the hill or get off the gas it will go back to normal. I'm lost as to where or what is wrong. Hoping you guys can help point me in the right direction. Thanks!!

 

Assuming you have filled the coolant I would check and make sure the secondary electric and AC cooling fan is coming on. You should easily hear it from inside the car. With the AC off go up the hill and listen for the fan to come on. If you don't hear it then that is the problem. If you do not have one (no AC) then you may want to install one.
You should check the fan clutch on the engine fan too. It may not come on. You can raise the hood and put a piece of cardboard over the radiator. Run the engine and watch the fans to see what happens. You may want to change the thermostat since it is so easy to get to and cheap.

 

Check your coolant level. If it only overheats going up hills and not while idling or low speed driving you're probably looking at a new radiator.