AC not working at speed
 

So I went for a hwy drive and the ac doesn't work for Sh when doing 75-90mph, I did do a couple hard pulls... oil and coolant temps never went over 223/221 outside temp was low 90's. Car has an oil cooler, CSF radiator, and air to air intercooler for the SC. When I got into town after a 2 hr drive and slowed down came to a couple stops the AC works normally.... what could cause this?