I am having problems of icing in a cooler, the cooler is approx 50'x100'x 30'. My temp goal is 34-38 degrees Farinheight, all product entered to room is also 34-38 degrees. I have three evaporators two for one compressor and one large Krack on its own compressor.All are R-22. I am using a dual controller I have had them set at 35 with 2 degree diff, They are set to alternate in air defrost . I know I am under refrigerated, but the system has worked for a long time. About three weeks ago our outside temps were higher than normal by 15 plus degrees My Krack sm25 started icing really bad I have been fighting ice ever since.The defrost clock had issues so i repaced it the controller went next so I replaced it I moved the probe in a more central location I haved played with the diff I checked the compressor found a small leak in the oil saftey switch so I replaced it and added 30 lbs of gas I noted it has a EPR Today we changed the evap pressure from 38 to 45 pounds. One week later the outside temp went back to normal but my problem still exists The people I work for , me and my refrig guy are all frusterated. Can any one give me some ideas?