good morning it is a very common brand atlas brand in Costa Rica I do not have nitrogen so I proceeded to put a service valve in the capillary and seal the return tube at the other end then I emptied for about 20 min and after several hours the empty step from -27 to -15 apparently in the evaporator would be the problem, it should be noted that check well that the weld sticks of the service valve to the capillary and the outlet to the return tube were well welded My question is could that test that I did make the evaporator empty from the capillary to the return tube be reliable and leave it overnight measuring the vacuum?

The test is correct. Attention if you leave the clocks connected you may have an escape in the same manifold. It would be ideal to test with nitrogen .. why do you suppose there is a leak?