1996 Chevy K1500 4WD, Auto, 5.7L, recent work includes alternator 6K miles ago, New brake booster and front brakes, rotors and calipers, battery, plugs, cap, rotor, filters and belt all within 2K miles ago. Mileage is 153K. AC blows cool, not super cold, in shade and when running down the freeway. At stops and slow speeds, it starts getting warmer. Picked up a can of Super freeze 134 with gage attached to it, hooked up the gage and the pressure was way up in the red. I did not add the gas at that time. I don't have a set of real gages to tell numbers. Expansion valve? Orifice tube? Clog? I just donated for previous question and had 25 views but no help Hopefully this one is easier. Thanks.