today i had to change a compressor on a foster 2door upright freezer i reclaimed the gas from it weighed out nearly a kilo of 404a plate says 600grams (wonder why the compressor failed ) so i remomoved old compressor it smelled a bit but it also had the bright green dye in to find leaks what i struggle to understand is with a system that small why add it if you cant find a leak on a system that small its time to become a plumber full time lol fitted new comp changed drier brazed in shrader valve on condenser out let i fitted a flare drier so i could purge nitrogen through capillary for 10mins at about 5psi to make sure it clear of any blockages pressure tested it to 20bar fitted vac pump got 6 torr in 20 min was well impressed 2torr in 45min have worked on all the other units in this kitchen and have had to do triple evac on all of them at least once after changing evaps or capillary or both previous contractor just went along and added gas moisture probs i have had on other cabs are unbelieveable this compressor change went brilliantly and i only put in 600grams of 404a and it came down to temp in an hr amazing you dont have to over charge unit if you do everything by the book and make sure theres no moisture or air in system oh and top tip to any one who works on these and has a leak they cant find change the evap an capillary especially on the old units with hot gas defrost the drier is good idea as well and fit a schrader valve in discharge line how can you vac it out properly if you dont ? oh and a mag lifter on hot gas solanoid makes a good professional touch as well