GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to familiarize yourself with the system functions. Refer to Control Assembly Description .

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.
    • If equipped, inspect the passenger compartment Air Filter for complaints of reduced air flow.

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:

    •  Blower Motor Inoperative at Any Speed
    •  Blower Motor Inoperative in One Speed Only
    •  Blower Motor Always On
    •  Air Delivery Improper
    •  Heater Air Inoperative
    •  Defrost Air Inoperative
    •  Instrument Panel Outlets Inoperative
    •  Air Recirculation Inoperative
    •  Air Recirculation Always On
    •  Driver and Passenger Temperature Control Inoperative CJ3
    •  Driver Temperature Control Inoperative CJ3
    •  Passenger Temperature Control Inoperative CJ3
    •  Temperature Control Inoperative C60
    •  Defrosting Insufficient in Heating, Ventilation and Air Conditioning
    •  Cooling Insufficient - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning
    •  Heating Insufficient in Heating, Ventilation and Air Conditioning
    •  Noise Diagnosis in Heating, Ventilation and Air Conditioning
    •  Cold Drafts on Floor in Heating, Ventilation and Air Conditioning
    •  Odor Diagnosis in Heating, Ventilation and Air Conditioning