Hi,. my car ('86 420) has a low-pressure r-134-A adaptor on the high side, at the condenser, so I can't connect to the high side when testing. It has a Schrader valve in it and screws onto a male fitting, which looks like Acme threads, on the condenser tubing. At Polar, they have this part listed for the low side, and the high side is for 3/16th threads. How can I get the correct adaptor so I can connect my gauge set to the high side?