Need help! AC issue (leaks)

Had my AC charged up and it worked for 2 days and stop working.

Charged again with UV dye, also pulled vaccumme on it and the pressure stayed consistent during the 15-20 mins time frame, 2 days later, leaked all out,

got under it inspected with uv light, did not see ANY leak, nothing, clean as it can be.

me and my mechanic suspected that the lines that goes into the rear AC has a leak somewhere and we could not see it from underneath.

one thing worth noting is that when the system is charged up, the rear ac did not blow cold air, but the front does.

Any suggestions?

my mechanic said that the simplest way to fix it is to cut the lines that feeds the rear ac and cap them off.

Does your Van have the icemaker? If so it could be inside the Icemaker as I could never find the source of my leak using dye externally until refrigerant oil started to pool at the refrigerator connection.