GM Service Manual Online
For 1990-2009 cars only

Important: Review the system operation in order to familiarise yourself with the system functions. Refer to:

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

Visual/Physical Inspection

    • Inspect for aftermarket devices which may 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 may cause the symptom.
    • Verify the A/C compressor turns and is not seized.
    • The A/C compressor will not operate in cold outside air temperatures. Refer to Air Temperature Description and Operation .
    • 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:
        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:

    •  Too Cold in Vehicle .
    •  Too Hot in Vehicle .