This is great! I'll have to print it. Appreciate the safety check list. The only daunting part is tracking down a trashed fridge and making a vacuum pump. I would have to go to one of the appliance junkyards arround here. The interest is there but not much time between my day job (prod. dev. Polymer Lithium batteries) and expanding family demands. Would have liked to rent one or buy a bench top vacuum pump like they sell for dry boxes, chem labs etc but they're probably too pricey as my budget would be arround $50.
I would think a predetermined mass of refrigerant would be accurate based on MB's conversion data between refrigerants. In any case I like the idea of using the gauges as it's a "window" into the system. If the condensor was changed (it looks pretty new) that could also affect the amount needed I would guess.