Abstract: A coupling for attachment to air conditioning systems to prevent leakage of refrigerant fluid during testing and servicing thereof. The coupling includes an elongated outer housing adapted to be attached at one end to an air conditioning system. The housing is provided with an axial bore in which is positioned an inner cylindrical body member having longitudinal ducts, which member is movable longitudinally with respect to the outer housing. One end of the inner body member is adapted to be selectively engaged with testing equipment or a refrigerant fluid supply. A portion of the inner housing is aligned with a valve of the air conditioning system which is actuated thereby upon longitudinal movement of the inner body member, thereby permitting refrigerant fluid to flow through the ducts in the inner body member from the refrigerant supply to the air conditioning system. Means carried by the inner body member facilitate longitudinal movement thereof.