Diagnostic Aids

WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.

If complaint was insufficient cooling, problem may be caused by inoperative cooling fan(s) or faulty A/C refrigerant fan request switch. Engine cooling fan(s) should turn on when A/C pressure exceeds a value to open switch, causing ECM to energize cooling fan relay(s). See CHART C-12 for cooling fan diagnosis. If fan operates correctly, ensure A/C system refrigerant charge is okay.

Fig 1: A/C Clutch Circuit Schematic (3.1L - Front A/C Only)

Courtesy of GENERAL MOTORS CORP.

Fig 2: A/C Clutch Circuit Flow Chart, (3.1L - Front A/C Only)

Courtesy of GENERAL MOTORS CORP.