Overheating

I have a 95 Metro with 1.3, auto. When running on the freeway with the A/C on it starts to run hot. It doesn't make it to the red zone but almost. It usually stays at the half way point. Even when idiling in traffic. With the A/C off it stays at the half point. It has a new radiator and cap and t-stat. It runs great other than this problem. The engine has 143,000 miles. any ideas would be appricated. Thanks