make sure that both the AC matrix and radiator core is not partly blocked with leaves, paper or any other muck. Try giving them a good wash, not a pressure wash, but using a hosepipe. Wash them out from both directions, thru the grille and from the engine side. Also, if you can disconnect the top and bottom hoses and then see how the water flows thru the radiator using the hose on max flow. Make sure you fill up with the proper antifreeze and bleed the system if it needs it.