You unsolder the suction line and cap tube remove drier cuz you're gonna replace it anyway With the process tube adaptor it's a fitting you put on the tubing with a temporary valve that will allow you to put your gages or hoses on it the the nitrogen with force the restriction through the cap tube Thats where the R-11 comes in it's a solvent that will flush any contaminants you do the same with the hi side then I solder it back together and flush again. They claim a R134A system should only be open for 20 minutes or less which is impossible but you hurry as fast as you can with out mistakes because R134A is so suseptible to moisture. But if your restriction is solder that dripped into the tube and plugged it it wont help that