I am still missing something, I have a customer with a walk in cooler in a bar its a 409a system, complaint was the evap. ices up intermittently at first now it ices up and wont get down to temp. The customer has done a lot of work on the cooler, the panel seals were all not sealed, the ceiling was falling in and the unit could not keep up. Now they have sealed the cooler, added insulation and covered that with steel siding, along with replacing and reinsulating the floor, all thats left is to align the door so it seals better. At first they had the unit running and it would pull down to 40-42 degrees. Now it runs 48-50. I stopped and checked the charge and operation out, liq press 160#=106f, suction 32#=36f, box 48-50, ambient for the condenser 80-85. Liquid temp was 99f, suction at the evap outlet/txv bulb 47f, air outlet from the evap about 50-52. The sight glass is clear, this system has a reciever, my subcooling was about 6, and super heat 10-11 at the evap outlet/txv bulb. I added some 409a to increase my subcooling to see if that would help, but not much difference, I have tried lowering and increasing the superheat to try and get my air outlet temp down, when I left I had about 6 superheat at the evap outlet, 12-15 at the compressor, 8 subcooling, 165 liq press=108f 99f liq line, 30# suction=36f, 40f evap outlet, 48-51f at the compressor, my evap outlet was about 46-48f. I checked with the customer this am and the box got down to about 42-43 but the coil again is starting to ice up. The thermostat does shut the unit off and the system pumps down and stays. I am missing something I dont understant why I cant adjust this system to maintain 38-42 for this walk in cooler. As is they are happy it is keeping the keg beer and can beer cold so when they move it to the bar it is almost at the temp they want but the health department is on them about the walk in temp as they serve food and want to store the food in the walk in but cant get the temp down low enough. Is there something I am missing?? My next step is going to be to pull the charge out, and add it back in till the sight glass clears and see if that makes a difference. I dont see where this system is over or under charged, the txv is brand new. This is the 3d walk in with 409a and I have struggled with all 3. I work on quite a few walk in coolers and freezers but cant seem to get the readings I want with 409a. My other thought is as far as I know when this cooler was set up it was for a beer cooler only in the last year has the customer started serving food, maybe this set up is not designed to go lower than 45??