Had my car regassed at the end of last year maybe October time by a mobile specialist. He assured me that there were no leaks in the system. Gas lasted a few months when the car started hissing again I think in March/April on initial AC startup. So I called him back - he had put in the dye when he regassed it but again could not find any leaks under UV inspection. Its now again doing the same thing so there is a leak somewhere but again I tried to look for it with a UV light but no luck - the only thing florescing was the duo valve - is this normal? Any advice of where to look for a leak or what to do next?