Errattic temperatures in Freezer
Check out "victory-refrig.com" for manuals, diagrams, etc.
Cap tube systems are "critical charge systems". Can be difficult to get right. You did not mention pressures that you had. The split on the evap vs.box temp is almost always 10 degrees for freezers. If you want a -10 box, your evap needs to be -20. As a general rule of thumb, you want the high side to be "ambient +30". This seems to work most every time. Your problem might be operations related. Them leaving the door open alot and so on. It could also be a problem with the evap fan or the control to it. It could also be that since there had been a problem with the unit, they are now constantly checking it. Could be checking during a defrost cycle. When your box is at 0 degrees, your pressure should be about a -10 and no less that a -15 degree for the evap. You may have to babysit this thing and see how far it will pull down. You may have a weak compressor. Also, I have had many Hobart freezers fail due to dirty condensers. This causes the oil in cap tube systems to gel and clog up the cap tubes. The only fix is replacing the cap tube. There are alot of variables here so be patient, it's not going to be a quick fix. One last thing, since R404A can fractionate, you really need to pull the charge out and weigh in the correct charge with virgin refrigerant. This will eliminate 2 things. 1, it will ensure the correct amount of refrigerant and, 2 no chance of having a poor mixture of refrigerant in the system causing inconsistant readings and performance.
Hope this helps. And remember, cap tube systems are performance measured by the amount of superheat just prior to the unit making temp and cutting off.
on Mar 07, 2009