I would suggest cleaning off the dirt from the base of the connector and looking for any numbers or brands. Because there are 3 different styles that look very similar, ISO 5675 which is the standard AG connector, but some compacts and other equipment use ISO 7241-A or ISO 7241-B. The 1/2 inch ISO 5675 AG connector will plug into the ISO 7241-A, but will have a flow restriction because of the different lengths of the Poppet tip . Also the slightly different diameter of the tip will over time start leaking.