A service device connects to a service port of a pressurized system. The device includes a valve opening member for opening a valve within the port. The position of the valve opening member within the connector is adjustable or self-adjusting. The adjustable valve opening member allows the valve in the service port to be opened fully by the connector over a range of valve positions within the port. The device can attach to a service unit for servicing the pressurized system. The system can be an air conditioning or refrigeration system.