My dodge ram is getting hot when I run the AC, especially if it's sitting still for any period of time at all, even at red lights. I replaced the factory thermostat with a 180 degree and replaced the antifreeze/coolant but this did not help. I believe the new thermostat is working properly as you can see the temp gauge drop when it opens but for some reason the water isn't cooling off enough once it has ran for 15 or 20 minutes. I let it start to get hot yesterday and sprayed the radiator with water and it immediately starting cooling down. I'm guessing I have a radiator problem but would welcome any other suggestions before I go buy a new one. Also, if you know where I can buy a radiator larger than the factory 1 core please let me know. Thanks.

 

Are your fans kicking on? Also,are they kicking on at the right time? This could be the problem.At idle you don't have much air going into the engine which could explain why it would get hot then.Once your rolling,air is being forced in there helping cool it off.