A/C Issues - Losing gas

[rene525d]

Hi Guys,

I have to turn to you once again. Since I purchased the car in Winter I did not use the A/C on cool, however when the heat kicked in I noticed that the A/C is not cooling! It blows only 'air'. I took the car to an A/C workshop and he told me refrigerant was very low. He filled it up and I was good to go for 2-3 weeks, after which the same symptoms occurred. Took it back, filled it with gas again, and added some sort of yellow dye that glows in the dark to be able to identify the spot of the leak. Another 2 weeks pass and I am low on A/C gas once again. We spent a few hours in the evening trying to pinpoint the location of the leak to no avail. He even tried pressurizing the system with Nitrogen and it seems to hold well (1-2 hrs).

Any ideas how this refrigerant is being lost or from where? When I have the A/C on and the fan on low, I constantly hear a noise as if the refrigerant is constantly moving.