I have a relative who has a GHP system in his home.   It has a refrigerant leak.  The system will lose all of it's refrigerant within a week.

An HVAC tech who specializes in these systems charged the system and included a yellow dye-pack so that the source of the leak could be found.

A week later, the refrigerant was gone.   The HVAC tech returned and spent 4 hours attempting to find the leak.   When there was no sign of the dye, the HVAC tech pressurized the compressor, the evaporator coil, and the coax, each in turn and declared they did not have any leaks.  However, he doesn't know where the leak is.

Has anyone seen this before?  Where might the leak be?  Is it possible if there was a leak inside the coax between the refrigerant carrier and the water loop that the dye could have dissipated into the water loop but not be detected when pressurized?

Mike