i am in the process of converting to 134a. Every parts place I went to today sold a high and low side adapter fitting.....but all the high sides had no Schrader valve in them.....but look too deep for the original schrader to function correctly when hoses are attached for gauges. I looked online and found some with the schrader, so I ordered one...... But how are the ones without schrader valve supposed to work?