I arrived to our client home due to the unit not cooling properly. The unit was off but had a standing pressure of 153psi. I used nitrogen to add additional pressure to the existing refrigerant in the lines. I got the pressure up to 370psi. And I began to hear an audible hissing sound coming from the base of the outdoor condenser coil. I saw a visible oil spot where the hissing was coming from also. This spot was not present on the previous visits. I used soap bubbles and partially disassembled the unit to get access to the coil and accurately pin point the leak. I took pictures and videos of the leak and called Trane tech support. They had me send them pictures to start the warranty process for the mini split. I Spoke with Mrs Johnson regarding the situation and let her know that the unit is only under parts warranty and not labor warranty. We will communicate with her updates regarding the warranty equipment and status.