Hello
There will be a company that can make a new condensing unit using 134a or maybe off the shelf being 134a. they will need to know pipe sizes, model numbers if any and if you can take the unit to them they can match it. A refrigeration wholesaler maybe able to help you . someone in america will tell you. i know you have total line over there call them .They will point you in the right direction. there are companies in aus that do it.