I do intend to flush the system using Dura II, should have made that clear. My point was you need to blow compressed air through the systems for a good while after flushing it, and I have a compressor to do that.
As far as "nothing wrong with air con there" I'm not sure what you mean. I agree a/c should work 10 years. I never had an issue with my other cars, but this one worked maybe 18 months after buying it BRAND NEW. then the warranty dealer replacement worked 3 years at most. Looking online there are a bunch of people with similar problems. Am I only buying another 2-3 years with this repair?