Refrigerant System General Procedures

WARNING: This page is about a different car, the 2004 Mazda 3. However, it is still accessible from the selected car via links, so may be relevant.

Fully close the valves of the manifold gauge.
Connect the charging hoses to the high-and low-pressure side joints of the manifold gauge.
Connect the quick couplers to the ends of the charging hoses.
Connect the quick couplers to the charging valves.

Fig 1: Identifying Manifold Gauge, Charging Hose
Courtesy of MAZDA MOTORS CORP.