See if when you put the coolant in it it keeps it because it sure has a good loss since you found it without gas or if it is blocked or plugged in the capillary or filter, check if welding does not cover too much with the material of contribution such joints that You did restricting the passage of gas check and comment. Pay attention to the low clock if when it turns on it is almost completely empty and then you stop the compressor and the pressure does not rise is blocked but keep in mind that you found it without gas and that is inevitably a waste