You have to evacuate the system with an Evacuator.
The evacuator will reach at least 30 in/lbs of of vacuum in the system
which is enough to rid the system of any moisture.
The vacuum has to stay at least for 30 minutes to insure there are NO LEAKS.
If the system will NOT hold the vacuum then there is a leak, and the leak needs to be repaired.
Using a HAND VAC PUMP will not accomplish this.
Shreader valve is a spring loaded valve.
It is either open or closed.
There aren't any one way, or anyways to it.
If you don't press it down far enough, it won't open fully.
