how to tell if my heads are cracked on a 2002 hyundai sante fe on 2002 Hyundai Santa Fe

when on the freeway my temperature hand sometimes goes past the halfway mark

To check if the heads era cracked , they need to be removed from the engine and pressure tested. Probably be more cost effective to have a shop(that you trust) diagnose the overheating issue properly. Give them all the info you can as to the conditions when it overheats.
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if engine light is not on you can have a coolant flush and change the thermostat. test cooling fans if they come on when you have the ac on then there working