GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to learn the system functions. Refer to:

   •  Air Delivery Description and Operation
   •  Air Temperature Description and Operation

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 system components for obvious damage or for conditions which can cause the symptom.
    • The following could cause window fogging:
       - A wet carpet
       - High humidity
       - An interior water leak
       - Maximum passenger capacity
       - Blocked body pressure relief valves
    • Inspect the air distribution system for causes of reduced airflow:
       - Blocked air inlet vents or damaged air inlet vents
       - Blocked air outlet vents or damaged air outlet vents

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:

    •  Blower Motor Always On
    •  Blower Motor Inoperative
    •  Blower Motor Malfunction
    •  Too Hot in Vehicle
    •  Too Cold in Vehicle
    •  Air Delivery Improper
    •  Defrosting Insufficient in Heating, Ventilation and Air Conditioning
    •  Noise Diagnosis - Blower Motor in Heating, Ventilation and Air Conditioning
    •  Odor Diagnosis in Heating, Ventilation and Air Conditioning