5 hp semi-hermetic low temp walk in freezer, hot gas defrost, R-408. Replaced compressor over 1 year ago, after replacement I observed "milky oil in sight glass", closed expansion valve a bit, problem solved. After 6 months I inspected unit, same oil problem and suction line frozen ( evaporator clear) Installed an accumulator, seemed that the problem went away (this was winter season). Compressor is in a basement with a remote condenser. Spring is here and now the basement warmed up by around 10F to lets say 60F, think I should mention this. After a brief visit to the site I observed the accumulator frozen 3/4 up, suction frozen from the accumulator to the compressor valve but not frozen from the evaporator to the accumulator. What the hell am I missing? Is the equalizing line from the valve faulty? There is no crankcase heater ( I just bought one and will install in a few days just to gain some extra time b4 breakdown). This freezer was designed like 20 years ago and worked without major problems until 1.5 years ago. I serviced this unit for the last 10 years and now I'm lost. Thank you for any suggestions.