The r134a needs to be weighed with scales. These are linear compressors and exact weight is a must. It’s difficult to charge them going by the PSI. If it has 2 evaporators you’ll need to put the 3 way valve in neutral before pulling the charge and leave it in neutral to recharge.
I l am aware that I’m answering this 2 years too late, I’m known for never being in timer. Maybe someone will need this info one day and here it will be.