I just converted my A/C to 134a. All components were changed except the condenser. (Yes even the evaporator, fun, it was leaking on the initial charge) Anyway, it's been working well for a couple of weeks now. The true test came today when I took a little road trip. (about 300 round trip miles) On the turnpike around 80 mph it was blowing cool not cold air. I could tell when the a/c clutch turned on by watching the volt guage (electric fan with a/c relay). It would engage for only about 2 seconds at about 5 second intervals. It was about 105 in Oklahoma today and this was about the hottest part of the day. Temp in the car was tolerable but not cool. Pressure switch was replaced at conversion, backed the adjustment screw off 1/4 turn upon returning since I forgot to when I replaced it. I don't know if that helped or not yet. Seems to work fine around town though. Any other suggestions? Thanks......