2005 Chevy Cavalier overheating when idling, AC turns hot when idling

Hi friends, I have some overheating issues with my car.

My symptoms are that when I idle on a very hot day here in vegas (it was almost 120 recently) the heat creeps up and up though nowhere near the red zone. The air conditioning also turns hot. However when I start driving then the engine temp starts to go down and the air conditioner becomes cold again.

A friend of mine is an amateur mechanic and he was nice enough to help me out cheaply and try and get the issue resolved. Initially he tried to replace the refrigerant, that did not have any effect and I did not really think it would but it is quick and cheap so we tried.

So then he changed out the fan and motor that goes next to the condensor. At first I thought that fixed it as the AC became much colder, but then I noticed the same results.

A day later the radiator kinda exploded and coolant went everywhere. He replaced that with a new one. I tried it out today and unfortunately same result.

He thinks it may simply be some air in the system causing overheating but the strange behavior happening at idling has stayed the same throughout the whole affair so I worry there more be more going on.

Before radiator issue coolant levels have always been fine, and no fluid has been detected anywhere. Oil seems to be fine, not too thick and no weird colors. No weird smell or fluid inside the cab. It's run like a dream until recently but I did hit a rock on a dirt road a few years ago and always worried that could have knocked something loose. I got weird noises a while but they kind of went away on their own.

Any suggestions as to what could be causing these symptoms?