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
    • 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

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 Operates at High Speed Only
    •  Blower Motor Inoperative in One Speed Only
    •  Blower Motor High Speed Inoperative
    •  Blower Motor Always On
    •  Air Delivery Improper
    •  Defrosting Insufficient in Heating, Ventilation and Air Conditioning.
    •  Heating Insufficient in Heating, Ventilation and Air Conditioning.
    •  Noise Diagnosis - Blower Motor in Heating, Ventilation and Air Conditioning.
    •  Noise Diagnosis - Air Conditioning (A/C) System in Heating, Ventilation and Air Conditioning.
    •  Odor Diagnosis in Heating, Ventilation and Air Conditioning.