I had to replace my engine on my 2003 legacy, (long story) The short version is never let anybody change your oil. When I go to recharge the AC the bubbling shown in the attached occures, What do I need to replace, Thank you.

subaru2003legacyAC.MOV

Recently, I had to replace one of those metal tubing connections to what I think is called a dryer. My metal tube developed a pin hole leak. I suspect from seeing your photo, that you either have a bad "O" ring where the tube attaches, or your tubing leaks. Clean the area as best you can, so you can better see where the bubbles are coming from, and what needs to be replaced. Suspect your tubing got bent during motor swap to cause your leak. I sourced replacement tubing from a wrecking yard.

 

Replacement "O" rings can be bought from auto parts store. Think mine came from Autozone, sold in a plastic pack with assorted size "O" rings. O ring I took off at the fitting was black in color, what I installed was green in color. It fit well.......guess color doesn't make any difference.

They are dirt cheap at subaru too.