AC auto gauges, or air conditioning triple gauges, are used when performing air conditioning maintenance tasks. There are two basic types of connectors in use for connecting triple gauges to your air conditioning system for maintenance and charging. These are the screw type and the quick connect type. With either type, the first step is to close the valves on the gauge set. The next step will be to disconnect. On the screw type, it’s just a matter of unscrewing the connector on the gauge hose. With the quick disconnect type, you will pull up on a skirt on the end of the hose, which will release the coupling.
For more info, see How to Recharge the Air Conditioner in Your Car