Diagnostic Aids

Incorrect fan operation or overheating may be caused by a mis-scaled coolant temperature sensor or faulty A/C pressure sensor. Check coolant sensor temperature using a Tech 1 scan tester. Sensor may have shifted out of calibration and should be replaced. See TEMPERATURE-TO-RESISTANCE VALUES table on Code 14 chart in appropriate TESTS W/CODES article in this section. Compare A/C pressure on Tech 1 scan tester with actual system pressure using a gauge. Replace A/C pressure sensor if faulty.

Fig 1: Chart C-12 Schematic (3.3L "N" Body) Cooling Fan Circuit Diagnosis

Courtesy of GENERAL MOTORS CORP.

Fig 2: Chart C-12 Flow Chart (1 Of 3)(3.3L "N" Body) Cooling Fan Circuit Diagnosis

Courtesy of GENERAL MOTORS CORP.