When i changed the hoses and coolant last year i used this refilling system and it worked great. It creates a vacuum and just sucks all the coolant back in no air gaps. i have used it on my sons car also. It sucked in about 8 gallons in 5 min. it also lets you know if you have a leak.
https://www.amazon.com/gp/product/B01BW39HJS/ref=ppx_yo_dt_b_asin_title_o04_s01?ie=UTF8&psc=1
Just a follow up on my Norcold Amish unit. When I installed my new cooling unit it was cool weather and it worked ok but when summer hit it was a different story. When the outdoor temperature was 80 or above the refrigerator section was about 50 degrees. I added more fans to no avail. I called JC refrigeration and they asked me some questions and determined my new cooling unit was defective. I said I didn’t want another absorption unit and said I wanted the 12 volt dual compressor model. They sent it out to me in a few days no charge. I just installed it a few days ago and wow I am impressed. This thing cools down in about two hours and the freezer gets to 0 on setting number 4. My Norcold box is in great shape. The door seals are good and the doors are stainless steel to match my other appliances. So now I have a residential refrigerator and no more fire hazard. I would recommend it to anyone and again JC Refrigeration was great to work with.