I seriously doubt if it's possible to just add to the system without completely emptying it and starting over, measuring all the ingredient back in. I used to work on big ammonia absorbers and I know the amounts of each component is VERY critical. Troubleshooting them is very tedious to determine if they need water,ammonia, the concoction of inhibitors or a combination. These rv fridges are even worse! They also have hydrogen in them to allow the ammonia to evaporate at high pressure(Daltons Law). The rv fridge techs I've talked to say they're junk if they leak any of the goodies. Good luck! Craig