If I had waited.....
I would have determined that my True cooler box had at least a partial restriction. The initial pressures were 4 # on low and 100# on high with a sat temp of 46 degrees. The next morning the pressures were -20# low and 55# high and a frosted cap from the evaporator to the loop in the cap tube. It took it well over 20 minutes to equalize on shut down. I will replace the dryer, and if necessary replace the cap using a gauge pin to determine the I.D. Either case, leak test and re-charge with 9 oz to spec plus an extra bump for hoses. In the old days we would purge it with nitrogen with the lines open, then seal it up and trace it with nitrogen and freon and leak test and go from there. I get ahead of myself sometimes. My next question is if you were to add a refrigeration book to your library would it be Refrigeration and and Air conditioning technology by Bill Whitman, Bill Johnson edition 6. And what would your leak detector preference be. The Fieldpiece heated diode or the Yellowjacket Accu-probe. Also thinking of a couple of Fieldpiece data loggers, one with dual temp head and one with an amp head. I know back when my dad had the business, he used a rotary dual temp recorder, and that really saved a lot of time and took out the guesswork. Thanks in advance!
Sounds like you are low on refrigerant, not partially clogged, with those pressures.