The expansion valves are adjusted fully open and I cannot turn the stem anymore. The refrigerant has always been 507, and the system is about 12years old. The other freezers are all little high in temp running at the same temp about 8'f. It wouldn't be so bad but the ice cream is a little soft. There has been an evaporator changed in a bunker style cooler that did lose a lot of refrigerant. Receiver is approx 20 percent and liquid line Site glass is full. May fluctuate a bit