Wow! 3.9C - that's very cold. Is that from the face level vents? Mine struggles to get below about 12C there! I might revisit the regassing process. I assume the Viseton FS10 unit that comes with the engine is good enough for all its Ford applications, so what is it about our cars that makes it "struggle"? Even with the car design issues that Herman points out, the input to the cabin from the aircon should be industry standard cold to begin with.