Lurker here, working on walk-in today @ one of our stores. This particular store is not open 24 hours. Box was temping fine @ closing. When they opened 6 hours later, box temp was 60* according to manager. I was 2 1/2 hours away. When I arrived, box temp was 42*. Condensing unit is a Heatcraft, part # 89022701, R22, lineset relatively short @ 15'. Outdoor temp 88*. First thing I noticed was lack of condensation on suction line. Looked @ site glass. it was either full or empty. Connected gauges, Low side 22* (45psig) head was 106* (214psig) No subcooling. SH @ condenser was 45*. @ this point I decided sight glass was in fact empty. The box has 3 evaporators in it, each of which showing SH between 24 and 26* SH. Pressure @ each evaporator was also 45psig (22*) I had to damn near empty an entire 30lbs cylinder to fill my sight glass, give me 10* subcooling (head now @ 225psig, still seemed low to me with 88* ambient, although I'm probably wrong) and bring my SH (@ condenser) to 20*. SH @ each evap ranged from 12-14*. I observed no indication of a leak anywhere in the system. After an hour of run time, the box temp only dropped 2 degrees (to 40*, I was also working on a southern store fixtures display case, whole other story altogether) Anyway, sorry for the lengthy post. Anyone have any ideas as to why this box temp is so damned reluctant to fall into the 36-38* range?