GM Service Manual Online
For 1990-2009 cars only
  1. Perform the Diagnostic System Check before using the Symptom Tables in order to verify that all of the following are true:
  2. • There are no DTCs set.
    • The control module(s) can communicate via the serial data link.
  3. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
  4. •  Dual Zone Air Conditioning (A/C) System Description
    •  Operating Modes
    •  Purge Mode Description
    •  Programmer Description
    •  Control Assembly Description
    •  Control Assembly Description - Passenger

Visual/Physical Inspection

    • Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories in Wiring Systems.
    • Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

    •  Air Delivery Improper
    •  Air Delivery Improper - Auxiliary
    •  Air Temperature Control Inoperative
    •  Air Temperature Display Inaccurate
    •  Blower Has High Speed Only
    •  Blower Motor Always On
    •  Blower Motor Inoperative at Any Speed
    •  Blower Motor Speed Erratic
    •  Blower Motor Not Running - High Current Draw Key Off
    •  Cooling Insufficient - Air Conditioning (A/C) Inoperative
    •  Heating Insufficient
    •  HVAC Compressor Clutch Does Not Disengage
    •  HVAC Compressor Clutch Does Not Engage
    •  Noise Diagnosis - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning
    •  Noise Diagnosis - Blower Motor in Heating, Ventilation and Air Conditioning
    •  Odor Diagnosis in Heating, Ventilation and Air Conditioning