[F.A.A.benny]

Fill the system with nitrogen. Spray soapy water on all components. Not just the fittings. When you say you rebuilt the system what exactly did you do to warrant calling it a rebuild. A proper rebuild will include, among other things, having leaked check evap and condenser, replaced hoses. The compressor should have a double lip seal installed also. should have no leaks from components other than maybe a leak at a fitting.