I work at a school as maintence man. I got my refgerent cert. about 2 years ago. I've had 3 freezer problems in that time. About 4 years ago a company evacuted a freezer that had 502 ref and replaced it with AZ-50. the last few days its been running about7-10 degree F. I've cleaned the coil today with coil cleaner and water. It made no difference. My pressures and line temps are 320psi and 115 degrees F on the discharge and 28 psi and 66 degrees F on the suction side. The out doors temp was 81 degrees F. The condensing unit is in a vented storge room with the room temp of 95 degrees F. I added a shot of freon to it which did not help. the temp in the freezer is standing at 10 degrees. Is pressure and the hi side is to high? Is that why the freezer temp is warmer than it should be?
I know the defrost works an the evaperator coil is not iced up. I'm out of ideas.