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:

Manual HVAC Description and Operation

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.
    • Verify the A/C compressor clutch turns freely and is not seized.
    • The A/C compressor will not operate in cold outside air temperatures.
    • The following conditions may cause window fogging:
       - Wet carpet or mats
       - High humidity
       - Interior water leak
       - Blocked A/C evaporator drain tube
       - Maximum passenger capacity
       - Blocked body pressure relief valves
    • Inspect the air distribution system for causes of reduced air flow:
       - Obstructed or dirty passenger compartment air filter, if equipped
       - Blocked or damaged air inlet or outlet vents

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:

    •  Air Conditioning Compressor Malfunction
    •  Blower Motor Malfunction
    •  Air Temperature Malfunction