We do a lot of a/c installs and correcting what others have done. By far the biggest problem on 134A systems are they have been overfilled. Sight glasses should be outlawed. You got a good experienced tech that obviously knew of this situation and corrected it. On the old 12 systems you could get by with thinking it's hot today and the condensor in the sun so 300 or so on the high is ballpark. With 134A you read the chart for ambient temp and humidity and set the high side for the a that reading EXACTLY. The old belief that just a "tiny bit more" will help will drop your output temp by 20*.
