Our techs have been having a lot of service calls with new unit overcharged. Many of these units were started in spring with temps below 75 degrees.,which was never a problem with R22.
Units get very noisy,and customers call. Also it seems just a half pound charge sends gauges out of site.,more finicky! Any thought appreciated.
Follow the superheat or subcooling chart that comes with the unit and warm the house up to 70-75 and you should not have a problem. Can safely and accurately charge a system down to 65 deg F OAT. They probably kept adding gas to try get the pressures up when it was cold thinking it was undercharged and now you can have 1/2 to 1 lb or more overcharge. Beer can cold suction line method does not work with R410 units or any over 10 SEER
"Cut it twice and it is still too short".