The refrigerant service port valve for air conditioners has a valve body defining a main fluid conduit adapted for insertion into a coolant line using compression fittings at opposite ends of the conduit. A pedestal is mounted on the exterior conduit wall. The pedestal has a bore therethrough forming a lower service passage that enters the main fluid conduit, and an internally threaded blind bore parallel to the lower service passage. A slider is mounted on the pedestal, the slider having a male quick connect fitting defining an upper service passage. The upper service passage may be aligned with the lower service passage in an open position to service the system, or the slider may be moved to align the upper service passage with the blind bore to access a setscrew, which is raised partially into the upper service passage to lock the valve in a closed position.