A chime-in on an old thread. When I did the radiator cleaning mentioned above, that was in preparation for a cross-country trip from NC to Tucson in mid Aug - mid Sept and several trips between Tucson and Phoenix, and then returning to NC, with the car fully loaded plus myself and three dogs. It was blistering hot, at times 115-118 degrees according to the temp display in the car. At speed it would usually run one or two dots above the halfway mark, sometimes getting up to about 3/4 of the way. If sitting at idle for quite a while, it could get all the way to the last segment before red, so a little nerve-wracking. Not sure how this compares to modern cars where the temp gauge basically does not fluctuate, whereas ours gives you honest readings. Would be interesting to watch scan data on a modern car to see how hot they actually get.
As far as AC performance, with a properly charged and functioning system and running R134A, you should be seeing temps in the low 40s to upper 30s on med-low or low, and the car moving, and the AC has been running a while and cooled down the cabin. This does depend on humidity too. On this odyssey I took through the desert, I experienced what a difference no humidity in AZ makes vs super-humid NC. Even at 110+ the AC would blow ice cold. I did not have a temp gauge but the ease of the AC cooling the car was substantial. Made me understand how much cooling power to it takes to overcome humidity.
