WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Air Conditioning (A/C) Refrigerant Pressure Sensor
Courtesy of GENERAL MOTORS CORP.
Disconnect the air conditioning (A/C) refrigerant pressure sensor electrical connector (1).
Remove the A/C refrigerant pressure sensor (2).
Inspect and replace the O-ring seal (3) as necessary.