Reinstalled ac parts that had previously been deleted from my 71 Skylark that now has 455 in it. Had the radiator cleaned which is a original 3 core from the original engine. Have not had overheating problems until now in 95 degree heat. Just now tried ac since install in winter. The temp got up to 240 sitting still and made me nervous so I shut it off and temp returned to normal. Do I need a bigger 4 core radiator or do I need to just run water or what?