ok not an expert either but just a thought .there is an aerosol spray that detects ac leaks by spraying it along the lines etc when the system is charged with ac gas and the compressor is running if the gas leaks out the aerosol stuff reacts with same and gives an indicaton color .I would take a trip to your local friendly fefregeration fitting service for some friendly advise ..but as you say if you really want it sorted you will have to take it to a ford dealer and have it diagnosed andfixed professionally and id expect this to be expensive but then it might be a case of simply tightening a coupler and soted ..good luck with it ..s